研究者基本情報

• Ph.D., ブリティッシュ・コロンビア大学（カナダ）
• 獣医学修士, 北海道大学

• https://researchmap.jp/read0213061

• https://jglobal.jst.go.jp/detail?JGLOBAL_ID=200901069361883126

• 200901069361883126

• 生殖生理
• Reproductive Physiology

• ライフサイエンス, 獣医学

• 学士課程, 獣医学部
• 博士課程, 獣医学院

研究活動情報

• Effects of osteopontin treatment alone and in combination with hormonal therapy on endometrial epidermal growth factor concentration and fertility at the first insemination after calving in dairy cows
  Taiwo Kamardeen Bello; Takashi Tanida; Takayoshi Tagami; Yojiro Yanagawa; Seiji Katagiri
  Theriogenology, 254, 117812, 117812, Elsevier BV, 2026年04月
  研究論文（学術雑誌）
• In vivo ovarian temperature promotes the in vitro growth and developmental competence of oocytes derived from bovine early antral follicles
  Kohei Kawano; Kenichiro Sakaguchi; Yojiro Yanagawa; Seiji Katagiri
  Theriogenology, 238, 117371, 117371, Elsevier BV, 2025年02月, ［査読有り］, ［国際誌］
  英語, 研究論文（学術雑誌）, In cattle, the culture temperature used for the in vitro growth (IVG) of immature oocytes is generally 38.5 or 39.0 °C, which is close to the normal temperature in the vagina or rectum. However, the temperature in the in vivo ovarian tissue is approximately 1 °C lower (37.5 °C) than that in the vagina or rectum. Therefore, the generally accepted culture temperature may not be optimal for the IVG of bovine oocytes. Herein, we investigated the effects of culture temperature on the IVG of oocyte-cumulus granulosa complexes (OCGCs) derived from early antral follicles (0.5-1 mm in diameter). OCGCs were subjected to 12 days of IVG at temperatures of 37.5, 38.5, and 39.0 °C. OCGC viability and antrum formation were evaluated every 4 days. Estradiol-17β (E2) and progesterone (P4) production from OCGCs during the 1st, 2nd, and 3rd 4-day periods was evaluated by enzyme immunoassay. Viable OCGCs after IVG were subjected to in vitro maturation (IVM), in vitro fertilization, and embryo culture. Then, the nuclear status and diameter of oocytes after IVM, rates of cleavage and blastocysts, and cell number in blastocysts were evaluated. In addition, the mRNA expression of heat shock proteins (HSPs) in the granulosa cells and reduced glutathione (GSH) levels in oocytes after IVG were measured. The viability of OCGCs did not differ among the groups, whereas the rate of antrum formation on day 12 of IVG culture was highest in the 37.5 °C group (P < 0.05). P4 production did not differ among the groups; however, E2 production during days 8-12 tended to be higher in the 37.5 °C group than in the other two groups combined (P < 0.1). The mRNA expression of HSP70 and 90, and the GSH levels of oocytes, did not differ among the groups. The oocyte diameter after culture was larger in the 37.5 °C group than in the 39.0 °C group (P < 0.05), and that in the 38.5 °C group was intermediate between the other two groups. The rates of nuclear maturation and cleavage did not differ among the groups. However, the blastocyst rate was higher in the 37.5 and 38.5 °C groups than in the 39.0 °C group (P < 0.05). The cell number in the blastocysts in the 38.5 °C group was smaller than the in vivo-grown oocytes, while that in the 37.5 °C group and the in vivo-grown oocytes did not differ. In summary, OCGCs in the 37.5 °C group showed healthy morphology and steroidogenesis, as well as better growth and developmental competence of oocytes. Therefore, culture conditions close to the in vivo ovarian tissue temperature would be optimal for the IVG of immature bovine oocytes.
• Effects of heat stress on gene expression associated with antioxidant capacity of bovine early antral follicles
  Kohei KAWANO; Kenichiro SAKAGUCHI; Eri FURUKAWA; Nattapong NINPETCH; Yojiro YANAGAWA; Seiji KATAGIRI
  Journal of Veterinary Medical Science, Japanese Society of Veterinary Science, 2025年, ［査読有り］, ［国内誌］
  英語, 研究論文（学術雑誌）, Heat exposure at the physiological level of oocyte-cumulus-granulosa cell complexes (OCGCs) during in vitro growth (IVG) culture decreases the reduced glutathione (GSH) level of oocytes, an antioxidant, but its mechanism has been unclear. We subjected OCGCs to IVG for 4, 8, or 12 days and investigated the effects of heat exposure on the gene expression of cumulus-granulosa cells associated with antioxidant capacity. Heat exposure did not alter the expression of genes related to GSH synthesis or reuse. Conversely, heat exposure increased mRNA expression of superoxide dismutase 2 and decreased that of glutathione peroxidase 1, which are antioxidant enzymes. Ultimately, heat exposure alters the gene expression of antioxidant enzymes in growing follicles, which may indirectly decrease the GSH level of oocytes.
• Identification of an osteopontin structural element for the restoration of a normal endometrial epidermal growth factor (EGF) profile determined by the EGF concentration on day 3 of estrous cycle and pregnancy outcome in repeat breeder dairy cows.
  Takashi Tanida; Takayoshi Tagami; Yojiro Yanagawa; Seiji Katagiri
  Theriogenology, 231, 171, 181, 2025年01月01日, ［査読有り］, ［国際誌］
  英語, 研究論文（学術雑誌）, The loss of a cyclic change with two peaks of increased endometrial epidermal growth factor (EGF) concentration on days 2-4 and 13-14 during the estrous cycle has been linked to low fertility in repeat breeder (RB) cows. We have shown that an intravaginal infusion of osteopontin (OPN) restored the EGF profile in RB cows. The present study aimed to determine a structural element of OPN to restore the normal EGF profile and fertility. Holstein RB cows were diagnosed the EGF profile by a single examination of the endometrial EGF concentration on day 3 of the estrous cycle. Those with an altered EGF profile were intravaginally infused with OPN and its fragments on the day of insemination (day 0); the concentration of endometrial EGF was measured on day 3, and pregnancy was diagnosed on days 30-35. In Study 1, recombinant OPN (rOPN) (16 nmol), thrombin-cleaved N- and C-terminal fragments of rOPN (N-rOPN and C-rOPN, respectively), and a combination of these fragments (Th-rOPN) were infused (n = 13-20). The restoration rate of the normal EGF profile of the N-rOPN group (25.0 %) was a level in between the C-rOPN group (7.7 %) and both the rOPN (55.6 %) and Th-rOPN (64.3 %) groups. In Study 2, PBS (n = 47), rOPN (9.5 nmol, n = 83), and peptides of integrin binding motifs, GRGDSVAYGLK (peptide 1; 32, 320, and 1600 nmol), GRGDS (peptide 2; 320 and 1600 nmol), and SVAYGLK (peptide 3; 320 and 1600 nmol), were infused (n = 20-25). Restoration rates of the normal EGF profile of peptide 1 (320 and 1600 nmol) and peptide 3 (1600 nmol) groups (44.0-56.3 %) were comparable with those of the rOPN group (63.9 %) and higher than those of the PBS group (15.6 %). Restoration rates of the other groups were similar to those of the PBS group. Additional cows received infusions to determine the effect on fertility. Conception rates of the peptide 1 (320 and 1600 nmol; n = 50 each), peptide 3 (1600 nmol; n = 55), and rOPN (n = 111) groups (41.8-50.0 %) were comparable and higher than that of the PBS group (21.6 %, n = 75). In Study 3, PBS (n = 24), peptide 1 (320 nmol; n = 78), and GRGESVAYGLK peptide (peptide 4; 320 and 1600 nmol; n = 50 and 26, respectively) were infused. Restoration rates of the normal EGF profile of peptide 4 and PBS groups (16.0-19.2 %) were comparable and lower than those of the peptide 1 group (44.9 %). Thus, the SVAYGLK motif may be an OPN structural element to restore the normal EGF profile and fertility in RB cows, and the RGD motif may enhance its effect.
• 「動物細菌叢」の研究-ワンヘルスへの挑戦- 乳牛における子宮内細菌叢解析の産業利用の可能性
  八木沢 拓也; 内山 淳平; 片桐 成二
  日本細菌学雑誌, 79, 2, 38, 38, 日本細菌学会, 2024年06月
  日本語
• 「動物細菌叢」の研究-ワンヘルスへの挑戦- 乳牛における子宮内細菌叢解析の産業利用の可能性
  八木沢 拓也; 内山 淳平; 片桐 成二
  日本細菌学雑誌, 79, 2, 38, 38, 日本細菌学会, 2024年06月, ［査読有り］
  日本語
• ウシにおける子宮内細菌叢と分娩後の子宮環境および繁殖性との関連
  八木沢 拓也; 片桐 成二; 内山 淳平
  家畜感染症学会誌, 13, 2, 43, 49, 家畜感染症学会誌編集委員会, 2024年05月, ［査読有り］
  日本語
• Physiological high temperatures alter amino acid metabolism of bovine early antral follicles
  Kohei Kawano; Kenichiro Sakaguchi; Nattapong Ninpetch; Yojiro Yanagawa; Seiji Katagiri
  Journal of Reproduction and Development, 70, 3, 184, 191, 2024年03月, ［査読有り］, ［国内誌］
  英語, 研究論文（学術雑誌）, Heat stress reduces the developmental competence of bovine oocytes during the growth phase; however, the detailed mechanisms remain unclear. Amino acids play various critical roles in follicular development, including protein synthesis and as energy sources. We performed in vitro growth (IVG) culture of oocyte-cumulus-granulosa complexes (OCGCs) to assess the amino acid metabolism of small follicles at high temperatures. We isolated OCGCs from early antral follicles (0.5-1.0 mm) and subjected them to IVG culture for 12 days. OCGCs in the heat shock group were cultured under a temperature cycle of (38.5°C: 5 h, 39.5°C: 5 h, 40.5°C: 5 h, and 39.5°C: 9 h) to reproduce the body temperature of lactating cows under a hot environment. OCGCs in the control group were cultured at a constant temperature of 38.5°C for 24 h. Of the surviving OCGCs, those showing similar morphology and size between the groups were selected for amino acid analysis. We analyzed the free amino acids and their metabolites in the culture medium and calculated the depletion or appearance of molecular species. The depletion of three essential amino acids (isoleucine, leucine, and valine), two non-essential amino acids (aspartic acid and glycine), and ornithine was higher in the heat shock group (P < 0.05). Alanine depletion was lower in the heat shock group (P < 0.05). We concluded that heat exposure alters the amino acid metabolism of OCGCs isolated from early antral follicles, which might be involved with the diminished developmental potential of oocytes during summer.
• The value of evaluating luteal blood flow on the day of embryo transfer for recipient selection in Holstein lactating dairy cows
  Takashi Tanida; Itsuro Mukono; Mikiko Nakahashi; Daiki Miyano; Kurumi Miyazawa; Yojiro Yanagawa; Seiji Katagiri
  Japanese Journal of Veterinary Research, 71, 3, 72, 81, 2024年02月, ［査読有り］
• Changes in interleukin-2, -4, -6 and -8 expression in the postovulatory sow endometrium after artificial insemination based on conceived or failed to conceive
  Minami W. OKUYAMA; Masaharu MORIYOSHI; Seiji KATAGIRI
  Journal of Reproduction and Development, 70, 3, 192, 196, Japanese Society of Animal Reproduction, 2024年, ［査読有り］, ［国内誌］
  英語, 研究論文（学術雑誌）, The establishment and maintenance of a pregnancy requires proper interaction between the endocrine and immune systems in the uterus. Therefore, it is crucial to understand how changes in endometrial cytokine levels facilitate reproduction. This study aimed to investigate how representative cytokines sequentially changed in the endometrium and whether conception could be attributed to these changes. In this study, artificial insemination was performed twice in 160 sows and ovulation was examined every 3 h using transrectal ultrasonography. Uterine endometrial tissues were obtained via repeated biopsies at 2, 4, 6, 8, 12, 16, and 20 h after ovulation and interleukin (IL)-2, IL-4, IL-6, and IL-8 expression was examined using real-time polymerase chain reaction. The conception rate was 91.9%. The IL-2 levels showed no differences in conception or time. The expression peaks of IL-4 and IL-6 were delayed in sows that failed to conceive within 4-6 h and 2 h, respectively, compared to those that did conceive. In sows that conceived, IL-8 was highest after 2 h, and no difference was observed at other time point, regardless of conception. In sows that failed to conceive, the increase in IL-8 levels might have been cancelled or terminated before the first sampling time. These results highlight the importance of timely increases and subsequent declines in the levels of some cytokines for the establishment of pregnancy. Differences in uterine capacity start just after ovulation; detection and correction of these deviations can improve the reproductive efficiency of sows.
• Effects of recombinant osteopontin expressed in Escherichia coli on the recovery of the endometrial epidermal growth factor profile and fertility in repeat breeder dairy cows
  Takashi Tanida; Takayoshi Tagami; Hiroko Sato; Hay Mar Kyaw; Takeshi Fujikawa; Masashi Nagano; Kenji Momozawa; Yojiro Yanagawa; Seiji Katagiri
  Theriogenology, 217, 159, 168, Elsevier BV, 2024年01月, ［査読有り］, ［国際誌］
  英語, 研究論文（学術雑誌）, Endometrial epidermal growth factor (EGF) shows a cyclic change with two peaks on days 2-4 and days 13-14 of the estrous cycle. In repeat breeder cows, loss of the peaks has been associated with reduced fertility. By infusing seminal plasma (SP) and osteopontin (OPN) derived from SP and milk into the vagina, their EGF profile and fertility are restored. However, SP is difficult to obtain, and both SP and OPN can transmit infectious diseases. While OPN can be sourced from recombinant protein without this risk, recombinant bovine OPN (rOPN) expressed in Escherichia coli should be examined for its effects on the EGF profile, since it does not undergo posttranslational modification, which is important for its biological activity. In study 1, PBS, SP (0.5 mL), and rOPN (0.3 mg) were infused into the vagina at estrus (day 0) in 74, 37, and 105 repeat breeder Holstein cows, respectively, with an altered EGF profile. The endometrial EGF concentrations were measured on day 3. Some cows (n = 58, 20, and 83, respectively) were inseminated immediately before the infusion and then diagnosed for pregnancy between days 30 and 35. The normalization rate of the EGF profile and conception rate in the rOPN group (58.1 % and 47.0 %, respectively) were not significantly different from those in the SP group (62.2 % and 45.0 %, respectively) but higher than those in PBS group (29.7 % and 28.1 %, respectively) (P < 0.05). In study 2, repeat breeder cows with an altered EGF profile were infused with PBS (n = 18) and rOPN (n = 17), while fertile controls with a normal EGF profile (n = 18) were infused with PBS. Two or three embryos were transferred into cows on day 7 and then recovered on day 14. Embryo recovery rates of the rOPN and fertile groups were comparable (58.7 % vs. 58.3 %) but higher than that of the PBS group (58.7 % vs. 32.0 %) (P < 0.05). The embryo recovery rate of cows with normalized EGF profile was higher than that of cows with unnormalized EGF profile (64.4 % vs. 16.7 %) (P < 0.05). The embryo sizes of cows in the rOPN and fertile groups were comparable but larger than those in the PBS group (P < 0.05). However, the embryo size was not correlated to the corresponding endometrial EGF concentrations. In conclusion, rOPN without posttranslational modifications normalized the EGF profile in repeat breeder cows. Improved fertility by normalization of the EGF profile could be attributed partly to the increased embryo viability up to day 14.
• Effects of prostaglandin F2α treatment at follicular wave emergence on endometrial epidermal growth factor concentration on day of the next estrous cycle on fertility in dairy cows
  Vuong Tuan Phong; Takeshi Fujikawa; Kohei Kawano; Yojiro Yanagawa; Seiji Katagiri
  Theriogenology, 212, 189, 196, Elsevier, 2023年09月, ［査読有り］, ［国際誌］
  英語, 研究論文（学術雑誌）, Inadequate exposure to estradiol (E2) and progesterone (P4) may be the main causes of altered endometrial epidermal growth factor (EGF) profile, leading to reduced fertility in dairy cows. We hypothesized that PGF2α administration at different timings of the estrous cycle and stages of follicular development could change the profile of steroid hormones between luteolysis and estrus. This results in reduction in the peak concentration of endometrial EGF on day 3 (day 0 = estrus) in the next estrous cycle. In study 1, lactating Holstein cows were treated with PGF2α either on days 12-14 (selection phase group, n = 20) or on days 16-17 (control group, n = 24) of the estrous cycle. Blood samples were obtained before PGF2α treatment, 24 and 48 h after treatment, and on the day of estrus and ovulation for E2 and P4 assays. Endometrial tissues were collected by biopsy on day 3 for EGF assays. The duration from PGF2α treatment to both estrus and ovulation was longer in the selection phase group than in the control group (P < 0.05). The time between estrus and ovulation was longer in the selection phase group (P < 0.05). E2 concentrations were higher in the control group on the day of estrus (P < 0.05). P4 concentrations were not different between the groups. Endometrial EGF concentrations were lower in the selection phase group than in the control group (P < 0.05). In study 2, lactating Holstein cows were treated with PGF2α either on day 12 (selection phase group, n = 76) or day 16 (control group, n = 80). They were subjected to artificial insemination (AI) at estrus, and those that failed to ovulate by 24h after the first AI were subjected to second AI. On day 3, endometrial EGF concentration was determined. At estrus and on days 3 and 7, blood was collected for E2 and P4 assay from 20 randomly selected cows in each group before PGF2α treatment. The cows in the selection phase group exhibited lower EGF concentration, proportion of cows with normal EGF profile, and conception rate than cows in the control group (P < 0.05). On the day of estrus, E2 concentrations tended to be lower in the selection phase group than in the control group (P = 0.08). P4 concentrations were not different between the groups. These findings suggest that low E2 concentrations at estrus and low P4 concentrations for a prolonged period due to premature termination of CL in the absence of a dominant follicle are potential causes of altered endometrial EGF profile in dairy cows.
• The Difference in Subpopulation Structures in Sex-Sorted and Non-Sorted Semen by Discriminant Analysis of Bull Sperm Motility Data Collected by a Computer-Assisted Sperm Analysis System
  Chihiro Kanno; Kentaro Q. Sakamoto; Sung-Sik Kang; Yojiro Yanagawa; Seiji Katagiri; Masashi Nagano
  Andrologia, 2023, 1, 7, Hindawi Limited, 2023年05月24日, ［査読有り］
  研究論文（学術雑誌）, We examined the motility characteristics of sperm from sex-sorted bull semen as a model for low-quality (expected low conception rate) sperm compared to that of sperm from non-sorted semen (expected average conception rate) using cluster analysis followed by discriminant analysis. The results indicated that sex-sorted semen contained sperm with hyperactivation-like motility as the main subpopulation immediately after thawing, and this subpopulation decreased after 2 h of incubation. The main subpopulation in the non-sorted semen had progressive motility that was maintained during incubation. A conventional comparison of the mean values of kinematic parameters could not distinguish the samples. In conclusion, discriminant analysis using data from a cluster analysis of motile sperm may accurately describe differences in the structures of sperm motility subpopulations between low and normal fertility semen.
• Pre-maturational culture promotes the developmental competence of bovine oocytes derived from an 8-day in vitro growth culture system.
  Madalitso Chelenga; Yojiro Yanagawa; Seiji Katagiri; Masashi Nagano
  The Journal of reproduction and development, 69, 4, 214, 217, 2023年05月18日, ［査読有り］, ［国内誌］
  英語, 研究論文（学術雑誌）, In this study, we evaluated the effects of pre-maturational culture (pre-IVM) on the developmental competence of bovine oocytes derived from an 8-day in vitro growth (IVG) culture system. IVG oocytes were subjected to 5 h pre-IVM before in vitro maturation, followed by in vitro fertilization (IVF). The proportion of oocytes that progressed to the germinal vesicle breakdown stage was similar between groups with and without pre-IVM. Although metaphase II oocytes and cleavage rates after IVF were similar regardless of pre-IVM culture, the blastocyst rate was significantly higher in the group with pre-IVM (22.5%) than without pre-IVM (11.0%, P < 0.05). In conclusion, pre-IVM culture improved the developmental competence of bovine oocytes derived from an 8-day IVG system.
• Metataxonomic Analysis of the Uterine Microbiota Associated with Low Fertility in Dairy Cows Using Endometrial Tissues Prior to First Artificial Insemination
  Takuya Yagisawa; Jumpei Uchiyama; Iyo Takemura-Uchiyama; Shun Ando; Osamu Ichii; Hironobu Murakami; Osamu Matsushita; Seiji Katagiri
  Microbiology Spectrum, 11, 3, e0476422, 2023年05月, ［査読有り］, ［国際誌］
  英語, 研究論文（学術雑誌）
• Relationship between Amino Acid Metabolism and Bovine In Vitro Follicle Activation and Growth
  Kenichiro Sakaguchi; Kohei Kawano; Yuki Otani; Yojiro Yanagawa; Seiji Katagiri; Evelyn E. Telfer
  Animals, 13, 7, 1141, 1141, MDPI AG, 2023年03月23日, ［査読有り］, ［国際誌］
  英語, 研究論文（学術雑誌）, The amino acid metabolism of bovine follicles during in vitro growth (IVG) was evaluated to identify potential indicators of health during culture. The bovine ovarian cortex was sliced, prepared as strips, and cultured for 6 days. Tissue samples were examined histologically before and after 6 days of culture, and the degree of follicle activation was classified as either high or low based on the number of growing secondary follicles present (high: 7~11; low: 0~1). In a separate experiment, secondary follicles (diameter range: 100~200 μm) were manually isolated and cultured, and their growth was monitored for 6 days. Cultured follicles were classified as growth or degenerate based on diameter change during culture (growth: +60.5~74.1 μm; degenerate: −28~15.2 μm). Free amino acids and their metabolites were measured in the spent culture medium from each group. In cultured ovarian cortical strips, the concentration of α-aminoadipic acid was significantly higher in the low activation group than in the high group (p < 0.05), while those of methionine, lysine, and arginine were higher in the high activation group. In cultured isolated secondary follicles, concentrations of methionine, tyrosine, histidine, and hydroxyproline were higher in the degenerate group (p ≤ 0.05). In conclusion, amino acid metabolism has the potential to serve as an indicator of primordial follicle activation and subsequent growth rate during bovine IVG.
• Analysis of sequential ruminal temperature sensor data from dairy cows to identify cow subgroups by clustering and predict calving through supervised machine learning.
  Eri Furukawa; Yojiro Yanagawa; Akira Matsuzaki; Heejin Kim; Hanako Bai; Masashi Takahashi; Seiji Katagiri; Shogo Higaki
  The Journal of reproduction and development, 69, 2, 103, 108, 2023年02月17日, ［査読有り］, ［国内誌］
  英語, 研究論文（学術雑誌）, The present study investigated the applicability of a calving prediction model based on supervised machine learning of ruminal temperature (RT) data in dairy cows. The existence of cow subgroups for prepartum RT changes was also examined, and the predictive performance of the model was compared among these subgroups. RT data were collected from 24 Holstein cows at 10 min intervals using an RT sensor system. The average hourly RT was calculated and data were expressed as residual RTs (rRT = actual RT - mean RT for the same time on the previous three days). The mean rRT decreased beginning at approximately 48 h before calving to a low of -0.5°C at 5 h before calving. However, two cow subgroups were identified: cows with a late and small rRT decrease (Cluster 1, n = 9) and those with an early and large rRT decrease (Cluster 2, n = 15). A calving prediction model was developed using five features extracted from the sensor data (indicative of prepartum rRT changes) through a support vector machine. Cross-validation showed that calving within 24 h was predicted with a sensitivity of 87.5% (21/24) and precision of 77.8% (21/27). A significant difference in sensitivity was observed between Clusters 1 and 2 (66.7 vs. 100%, respectively), while none was observed for precision. Therefore, the model based on RT data with supervised machine learning has the potential to efficiently predict calving, although improvements for specific cow subgroups are required.
• Relationship between frame rates and subpopulation structure of bovine sperm divided by their motility analyzed by a computer‐assisted sperm analysis system
  Chihiro Kanno; Kang Sun‐Sik; Kentaro Q. Sakamoto; Yojiro Yanagawa; Seiji Katagiri; Masashi Nagano
  Animal Science Journal, 93, 1, e13796, Wiley, 2022年12月, ［査読有り］, ［国際誌］
  英語, 研究論文（学術雑誌）, The authors investigated the relationship between frame rates and subpopulation structure of bovine sperm divided by their motility analyzed by a computer-assisted sperm analysis (CASA). Kinematic parameters of bovine sperm incubated in Brackett & Oliphant medium with and without calcium ionophore for 0, 1, 5, 10, 15, 20, 25, and 30 min were evaluated by a CASA at 150 frames per second (fps) and analyzed structure of sperm motility subpopulation by cluster analysis. Then, we converted CASA data at 150 fps to 75, 50, and 30 fps and evaluated the structures of sperm motility subpopulation at different fps in each sperm by a discriminant analysis. As the results, the structure of sperm motility subpopulation was affected by frame rate. Sperm were divided into six clusters at 150, 75, and 50 fps; on the other hand, there were five clusters at 30 fps. Straight-line velocity was similar at all frame rates. However, as the frame rate became higher, curvilinear velocity and beat cross frequency of sperm head increased significantly, whereas lateral sperm head displacement decreased significantly. In conclusion, higher frame rate at 150 fps is recommended to capture the trajectory of sperm accurately by CASA in the present study.
• Simultaneous free fatty acid elevations and accelerated desaturation in plasma and oocytes in early postpartum dairy cows under intensive feeding management
  Eri Furukawa; Zhen Chen; Tomoaki Kubo; Yue Wu; Koichiro Ueda; Madalitso Chelenga; Hitoshi Chiba; Yojiro Yanagawa; Seiji Katagiri; Masashi Nagano; Shu-Ping Hui
  Theriogenology, 193, 20, 29, Elsevier BV, 2022年09月, ［査読有り］, ［国際誌］
  英語, 研究論文（学術雑誌）, A severe negative energy balance and high circulating free fatty acids (FFA) in postpartum cows impair fertility. The lipotoxicity of FFA has been shown to decrease the quality of bovine oocytes in vitro. Therefore, excess FFA in cells is converted to triacylglycerol (TAG), a non-toxic form, to avoid lipotoxicity. We recently reported that the TAG content in oocytes was higher in postpartum lactating cows subjected to grazing management than in heifers (Theriogenology 176: 174-182, 2021). The present study investigated the compositions of the energy metabolism-related lipids, FFA and TAG, in the plasma and oocytes of cows at different lactation stages under indoor intensive feeding management in order to obtain insights into lipotoxicity in oocytes, particularly those in early postpartum cows. Blood and oocytes were collected from 20 lactating cows categorized into the following lactation groups: 20-30 days in milk (DIM) (n = 5), 40-50 DIM (n = 5), 60-80 DIM (n = 5), and 130-160 DIM (n = 5). Daily energy balance data were obtained for 3 weeks prior to oocyte collection using the ovum pick up (OPU) method. The contents and compositions of FFA and TAG in plasma and oocytes were analyzed using liquid chromatography-mass spectrometry. As expected, plasma FFA was high at 20-30 DIM, decreased by 50 DIM, and was maintained at a low level for the remainder of the experimental period. Similar changes were observed in oocyte FFA and TAG with DIM as plasma FFA. Oocyte FFA positively correlated with plasma FFA (P < 0.05), but negatively correlated with the mean energy balance 1 and 21 days before OPU (P < 0.05). Relationships were noted between the composition and content of FFA in plasma and oocytes, with the FFA 16:1/16:0 and 18:1/18:0 ratios positively correlating with the total amount of FFA (P < 0.05). Elevated oocyte FFA in cows in the early postpartum period under intensive feeding management suggested that oocytes were at a high risk of FFA lipotoxicity. Furthermore, the present results implied that the severe negative energy balance in the previous few weeks was closely related to increases in oocyte FFA, which supports the importance of long-term cow feeding management for preserving the quality of oocytes in the early postpartum period. The present results provide insights into the effects of high circulating FFA on the fertility of postpartum cows.
• Effects of the presence of a large follicle and a corpus luteum in bovine ovaries on nuclear maturation of oocytes and steroidogenesis of granulosa cells cultured as oocyte-cumulus-granulosa complexes derived from early antral follicles
  Kenichiro Sakaguchi; Kohei Kawano; Yojiro Yanagawa; Seiji Katagiri; Masashi Nagano
  Japanese Journal of Veterinary Research, 70, 2, 45, 56, 2022年08月, ［査読有り］
  英語, 研究論文（学術雑誌）
• Relationship between the timing of insemination based on estrus detected by the automatic activity monitoring system and conception rates using sex-sorted semen in Holstein dairy cattle.
  Eri Furukawa; Chihiro Kanno; Yojiro Yanagawa; Seiji Katagiri; Masashi Nagano
  The Journal of reproduction and development, 68, 4, 295, 298, 2022年05月30日, ［査読有り］, ［国内誌］
  英語, 研究論文（学術雑誌）, We investigated the optimal timing of artificial insemination (AI) for achieving pregnancy according to the onset/end of estrus detected by an accelerometer system in Holstein cattle. The conception rates of conventional semen were used as a reference. The conception rate from AI of sex-sorted semen was higher at -4 to 4 h (57.1%) from the end of estrus than those at -12 to -4 h (37.7%) and 12-20 h (30.3%), whereas AI at 4-12 h showed an intermediate conception rate (47.4%). Conversely, conception rates were similar in AI performed between 0 and 32 h from the onset of estrus. Regarding conventional semen, the interval from the onset and end of estrus did not affect conception rates. The present results suggest that the time of the end of estrus is the better indicator of optimal AI timing for sex-sorted semen than the onset of estrus.
• Effect of heat exposure on the growth and developmental competence of bovine oocytes derived from early antral follicles.
  Kohei Kawano; Kenichiro Sakaguchi; Chelenga Madalitso; Nattapong Ninpetch; Shintaro Kobayashi; Eri Furukawa; Yojiro Yanagawa; Seiji Katagiri
  Scientific reports, 12, 1, 8857, 8857, 2022年05月25日, ［査読有り］, ［国際誌］
  英語, 研究論文（学術雑誌）, In dairy cows, low fertility caused by summer heat stress continues into the cooler autumn season. This can be caused by impaired oocyte quality in small growing follicles during summer. Here, we subjected oocyte-cumulus-granulosa complexes (OCGCs) derived from early antral follicles (0.5-1 mm) to in vitro growth (IVG) culture under two different temperature settings (the control and heat shock groups), and evaluated effects of heat exposure on growth and developmental competence of oocytes, factors affecting the developmental competence of oocytes (steroidogenesis of granulosa cells, oxidative stress in oocytes, and cell-to-cell communication between oocytes and somatic cells). Oocyte diameters after culture were smaller in the heat shock group. Although nuclear maturation and cleavage rates were similar between the groups, blastocyst rates were lower in the heat shock group (0.0%) than in the control group (27.7%), and reduced glutathione (GSH) levels in oocytes were lower in the heat shock group. Supplementation of cysteine, which stimulates GSH synthesis, increased GSH level and improved blastocyst rate of heat shocked oocytes (27.9%). These results suggest that heat exposure impairs the growth and developmental competence of oocytes in early antral follicles through GSH depletion, which can induce low fertility during summer and the following autumn.
• Effects of milk osteopontin on the endometrial epidermal growth factor profile and restoration of fertility in repeat breeder dairy cows
  Hay Mar Kyaw; Hiroko Sato; Takayoshi Tagami; Yojiro Yanagawa; Masashi Nagano; Seiji Katagiri
  Theriogenology, 184, 26, 33, Elsevier BV, 2022年05月, ［査読有り］, ［国際誌］
  英語, 研究論文（学術雑誌）, Endometrial epidermal growth factor (EGF) shows a cyclic change with two peaks on Days 2-4 and 13-14 during the estrous cycle. An altered (i.e., loss of the two peaks) profile has been linked to reduced fertility in repeat breeder cows. We previously demonstrated that a form of osteopontin (OPN), with a molecular weight of 29 kDa and found in bull seminal plasma (SP), normalized the EGF profile and restored fertility in repeat breeder cows. OPN has many molecular forms due to post-translational modifications and is abundant in bovine milk. The purpose of the present study was to investigate whether mOPN normalizes the endometrial EGF profile and restores fertility in repeat breeder dairy cows with an altered EGF profile. OPN was separated by one-step anion-exchange column chromatography from the whey of bovine milk. Purified mOPN was verified by Western blotting and peptide mass fingerprinting analyses. The OPN fraction showed three major protein bands of 61, 37 and 31 kDa (peptides I, II, and III, respectively) on SDS-PAGE. All three major bands were identified as OPNs by Western blotting and their tryptic peptide masses were matched at approximately 50, 40, and 10%, respectively, to the bovine OPN amino acid sequence by a peptide mass finger printing analysis. The three bands accounted for approximately 85% of the total protein content and 6-23 mg of OPN was obtained from 1 L of bovine milk. A lyophilized eluate containing 1.3 mg of mOPN (171 cows), 0.5 mL of frozen SP (62 cows), and PBS (84 cows) was infused at estrus into the vagina of repeat breeder cows with an altered EGF profile. Some of the cows treated with mOPN, SP, and PBS (46, 50, and 45 cows, respectively) were inseminated immediately before the infusion and then examined for pregnancy between Days 60 and 65. The rate at which mOPN to normalize the EGF profile (56.1%) was similar to that of SP (58.1%) and higher than that of PBS (23.8%) (P < 0.05). The conception rate after the infusion of mOPN (43.5%) was similar to that of SP (40.0%) and higher than that of PBS (22.2%) (P < 0.05). The present results indicate that the infusion of mOPN into the vagina is a treatment option for repeat breeder cows with an altered EGF profile. Further studies are needed to compare the capacity of the three OPN molecules in milk to normalize the EGF profile, together with their molecular characteristics due to post-translational modifications.
• Semen collection by urethral catheterization and electro-ejaculation with different voltages, and the effect of holding temperature and cooling rate before cryopreservation on semen quality in the Japanese macaque (Macaca fuscata).
  Noboru Takaesu; Chihiro Kanno; Kosuke Sugimoto; Masashi Nagano; Akihisa Kaneko; Yoriko Indo; Hiroo Imai; Hirohisa Hirai; Munehiro Okamoto; Mariko Sashika; Michito Shimozuru; Seiji Katagiri; Toshio Tsubota; Yojiro Yanagawa
  The Journal of veterinary medical science, 84, 3, 429, 438, 2022年03月15日, ［査読有り］, ［国内誌］
  英語, 研究論文（学術雑誌）, In the Japanese macaque, semen has been collected by electro-ejaculation (EE), using the higher voltage stimuli compared to other species including genus Macaca. Semen coagulates immediately after ejaculation, which makes difficult to produce high-quality semen for artificial insemination. Recently, semen collection using urethral catheterization (UC) has been reported in carnivore and this technique may allow semen collection without coagulation in a less invasive manner. Further, the temporal preservation temperature and cooling rate of semen during cryopreservation affect post thawing sperm quality. In this study, to improve semen quality and quantity, as well as the animal welfare, semen collection was performed by EE with high (5-15 V) or low (3-6 V) voltage, UC and a combination of the two (EE-UC). It has been suggested that a high voltage is necessary for semen collection, but 10 V stimulation was effective enough and 15 V is for additional sperm collection. Also, liquid semen was collected by EE-UC and this could increase the total number of sperm. Further, to improve the post thawing sperm motility, semen was kept at four temperatures (4, 15, 25 and 37°C) for 60 min, and processed with two cooling procedures (slow cooling before second dilution and fast cooling after second dilution). Holding semen at 25°C and fast cooling after the second dilution maintained progressive motile sperm rate. The present results will contribute to the improvement of semen collection and animal welfare of Japanese macaques.
• Leptin receptor expression and its change in association with the normalization of EGF profile after seminal plasma treatment in repeat breeder dairy cows.
  Nattapong Ninpetch; Dagvajamts Badrakh; Kohei Kawano; Yojiro Yanagawa; Masashi Nagano; Seiji Katagiri
  The Journal of reproduction and development, 68, 3, 209, 215, 2022年02月28日, ［査読有り］, ［国内誌］
  英語, 研究論文（学術雑誌）, Factors associated with high milk production levels have been linked to alterations in the endometrial epidermal growth factor (EGF) profile, a cause of reduced fertility in dairy cows. Therefore, we examined the leptin system that connects nutritional status and reproduction in dairy cattle related to reduced fertility in repeat breeder cows. Plasma leptin concentrations were measured in 18 heifers, 20 high-yielding control cows, and 26 repeat breeder cows, showing an altered EGF profile. Then, all repeat breeder cows were infused with seminal plasma (SP) into the vagina at the next estrus to normalize the EGF profile, while heifers and control cows were infused with vehicle alone. All animals were examined for EGF profiles. Eighteen repeat breeder cows, nine heifers, and nine control cows were also determined for leptin receptor (Ob-R) expression levels in the estrous cycle before and after the infusion. SP normalized the EGF profile in 53.8% of the repeat breeder cows. Leptin concentrations were similar in all groups, regardless of the treatment results for the EGF profile. In contrast, Ob-R levels in repeat breeder and control cows were similar and higher than those in heifers before SP treatment. Ob-R in repeat breeders showing a normal EGF profile after treatment decreased to an intermediate level between heifers and control cows and may provide a clue to take measures against repeat breeding in dairy cows.
• Ovulatory follicle size investigated by ultrasonography and single artificial insemination with ovulation induction in the Japanese macaque (Macaca fuscata)
  Noboru Takaesu; Masako Minami; Masashi Nagano; Akihisa Kaneko; Yoriko Indo; Hiroo Imai; Hirohisa Hirai; Mariko Sashika; Michito Shimozuru; Munehiro Okamoto; Seiji Katagiri; Toshio Tsubota; Yojiro Yanagawa
  Japanese Journal of Veterinary Research, 70, 1, 5, 17, 2022年02月, ［査読有り］
  英語, 研究論文（学術雑誌）
• Effects of heat stress on the endometrial epidermal growth factor profile and fertility in dairy cows.
  Kohei Kawano; Yojiro Yanagawa; Masashi Nagano; Seiji Katagiri
  The Journal of reproduction and development, 68, 2, 144, 151, 2022年01月28日, ［査読有り］, ［国内誌］
  英語, 研究論文（学術雑誌）, The endometrial epidermal growth factor profile is an indicator of uterine function and fertility in cattle. The present study aimed to investigate the effects of heat stress on the endometrial EGF profile and fertility in lactating Holstein cows. The endometrial EGF profiles of 365 cows in the Hokkaido and Kyushu regions were examined between June and September (heat stress period, n = 211) and between October and January (control period, n = 154). EGF profiles were investigated using uterine endometrial tissues obtained by biopsy 3 days after estrus (Day 3). The proportion of cows with an altered EGF profile was higher between June and September than between October and January (41.2 vs. 16.2%, P < 0.05). The effects of rectal temperature on Days 0 and 3 on the endometrial EGF profile were also assessed in cows (n = 79) between June and September in the Kyushu region. A single embryo was transferred to cow on Day 7 to evaluate fertility (n = 67). Regardless of the rectal temperature on Day 3, the proportion of cows with an altered EGF profile was higher (64.1 vs. 30.0%, P < 0.05) and the pregnancy rate after embryo transfer (ET) was lower (26.7 vs. 51.4%, P < 0.05) in cows with a rectal temperature ≥ 39.5°C on Day 0 than in cows with a rectal temperature < 39.5°C on Day 0. The present results indicate that alterations in the endometrial EGF profile induced by an elevated body temperature on Day 0 contributed to reductions in fertility in lactating dairy cows during the heat stress period.
• Plasma profile of follicle-stimulating hormone and sex steroid hormones after a single epidural administration of follicle-stimulating hormone via caudal vertebrae in Holstein dry cows.
  Kenichiro Sakaguchi; Tomoko Suda; Nattapong Ninpetch; Kohei Kawano; Yojiro Yanagawa; Seiji Katagiri; Koji Yoshioka; Masashi Nagano
  Animal science journal = Nihon chikusan Gakkaiho, 93, 1, e13696, 2022年01月, ［査読有り］, ［国際誌］
  英語, 研究論文（学術雑誌）, The conventional follicle-stimulating hormone (FSH) treatment for bovine superstimulation involves multiple intramuscular injections, which is stressful for animals and onerous. We herein investigated whether a single epidural injection of porcine FSH (pFSH) can induce superovulation and peripheral concentrations of pFSH and steroid hormones after the treatment in Holstein dry cows. We intramuscularly administered pFSH twice daily to three cows for 3 days (control) or a single epidural pFSH administration (epidural). Numbers of follicles (≥10 mm in diameter) at estrus and corpora lutea at luteal phase were counted by ultrasonography. Blood was sampled from 0 to 104 h after the first pFSH administration and plasma pFSH, progesterone, androstenedione, testosterone, and estradiol-17β concentrations were measured. Numbers of follicles (control: 18.3 ± 7.5, epidural: 15.7 ± 4.0; mean ± SD) and corpora lutea (control: 7.3 ± 4.2, epidural: 8.0 ± 2.6) were similar between both treatments. Plasma pFSH concentrations were higher in epidural than in control (p < 0.01). Although no significant differences were observed in progesterone, androstenedione, or estradiol-17β concentrations between the groups, testosterone concentrations were slightly lower with the epidural treatment than with the control treatment (p = 0.08). In conclusion, superovulation was induced by a single epidural injection of pFSH, which achieved higher pFSH level than the multiple injections in Holstein dry cows.
• Postpartum cows showed high oocyte triacylglycerols concurrently with high plasma free fatty acids
  Eri Furukawa; Zhen Chen; Hiroki Ueshiba; Yue Wu; Hitoshi Chiba; Yojiro Yanagawa; Seiji Katagiri; Masashi Nagano; Shu-Ping Hui
  Theriogenology, 176, 174, 182, Elsevier BV, 2021年12月, ［査読有り］
  研究論文（学術雑誌）
• Low oxygen environment and astaxanthin supplementation promote the developmental competence of bovine oocytes derived from early antral follicles during 8 days of in vitro growth in a gas-permeable culture device
  Madalitso Chelenga; Kenichiro Sakaguchi; Kohei Kawano; Eri Furukawa; Yojiro Yanagawa; Seiji Katagiri; Masashi Nagano
  Theriogenology, Elsevier BV, 2021年10月, ［査読有り］
  研究論文（学術雑誌）
• ホルスタイン種泌乳牛の分娩後日数及びボディコンディションスコアと卵子中トリアシルグリセロール量の関係
  古川 瑛理; 陳 震; 窪 友瑛; Madalitso Chelenga; Yue Wu; 千葉 仁志; 柳川 洋二郎; 片桐 成二; 惠 淑萍; 永野 昌志
  日本獣医学会学術集会講演要旨集, 164回, [GO, 5], (公社)日本獣医学会, 2021年09月, ［査読有り］
  日本語
• Effect of increased oxygen availability and astaxanthin supplementation on the growth, maturation and developmental competence of bovine oocytes derived from early antral follicles
  Madalitso Chelenga; Kenichiro Sakaguchi; Mohammed A. Abdel-Ghani; Yojiro Yanagawa; Seiji Katagiri; Masashi Nagano
  Theriogenology, 157, 341, 349, Elsevier BV, 2020年08月, ［査読有り］
  研究論文（学術雑誌）
• Identification of bovine seminal plasma proteins with an activity to normalize endometrial epidermal growth factor concentrations in repeat breeder cows
  Dagvajamts Badrakh; Atsushi Shirasawa; Yojiro Yanagawa; Masashi Nagano; Seiji Katagiri
  JAPANESE JOURNAL OF VETERINARY RESEARCH, 68, 2, 91, 103, 2020年05月, ［査読有り］, ［最終著者, 責任著者］
  英語, 研究論文（学術雑誌）
• Effect of seminal plasma infusion into the vagina on the normalization of endometrial epidermal growth factor concentrations and fertility in repeat breeder dairy cows.
  Dagvajamts Badrakh; Yojiro Yanagawa; Masashi Nagano; Seiji Katagiri
  The Journal of reproduction and development, 66, 2, 149, 154, 2020年01月28日, ［査読有り］, ［最終著者, 責任著者］, ［国内誌］
  英語, 研究論文（学術雑誌）, Epidermal growth factor (EGF) concentrations in the uterus show two peaks on days 2-4 and 13-14 during the estrous cycle in fertile cows. Loss of the two peaks has been linked to reduced fertility in repeat breeder cows. This study aimed to examine the effect of seminal plasma (SP) on normalizing endometrial EGF concentrations and restoring fertility in repeat breeder cows with low EGF concentrations on day 3. In study 1, we examined the effect of the deposition sites (the vagina and uterus) of SP on the endometrial EGF concentrations in repeat breeder cows. SP infusion into the vagina, but not uterus, on the first day of the estrus cycle (day 0) normalized the endometrial EGF concentrations (≥ 4.7 ng/g tissue weight) on day 3. In study 2, the effect of SP volume (0.5 and 10 ml of SP and 0.5 ml of SP diluted to 10 ml) on EGF concentration was examined. All groups with SP infusion had increased EGF concentrations on day 3, and cows with 10 ml of SP and 0.5 ml of SP diluted to 10 ml showed the highest levels of EGF concentrations. In study 3, we examined the effect of SP infusion on fertility. SP infusion normalized two peaks of endometrial EGF concentrations in about 60% of repeat breeder cows and produced more pregnancies than the controls (44.4 vs. 19.4%). Therefore, we concluded that SP may contain an activity to normalize the EGF profile and restore fertility in repeat breeder cows with altered EGF profiles.
• Monitoring follicular dynamics to determine estrus type and timing of ovulation induction in captive brown bears (Ursus arctos)
  Yoshiko TORII; Naoya MATSUMOTO; Hideyuki SAKAMOTO; Masashi NAGANO; Seiji KATAGIRI; Yojiro YANAGAWA
  Journal of Reproduction and Development, 66, 6, 563, 570, Japanese Society of Animal Reproduction, 2020年, ［査読有り］, ［国内誌］
  英語, 研究論文（学術雑誌）, It is important to understand ovarian physiology when developing an artificial insemination (AI) protocol. Brown bears (Ursus arctos) have a breeding season from May to July, although the type of estrus (polyestrus or monoestrus) is still contested. The present study aimed to define the ovarian dynamics, including follicular waves and ovulatory follicle size, and estrus type in brown bears. Six brown bears were used for ovarian ultrasonography; four were observed between April and October (before the start and after the end of the breeding season) and two in June (breeding season). In addition, we attempted to induce ovulation by administering a gonadotropin releasing hormone (GnRH) agonist. We observed follicular development in April in four bears, but follicles did not develop to greater than 6.0 mm in diameter until May. Thereafter, a group of follicles developed to more than 6.0 mm and grew as dominant follicles, except in one bear. After ovulation and subsequent corpus luteum (CL) formation, the follicular waves disappeared. Furthermore, in three bears treated with GnRH, follicles between 8.2 to 11.2 mm in diameter at the time of treatment ovulated and formed CLs. In two bears, follicles between 5.8 to 8.8 mm ovulated spontaneously within the observation interval. Our results suggest that brown bears may be monoestrous animals. Therefore, AI can only be performed once during the breeding season. Our results also suggest that dominant follicles larger than 8.0 mm are a suitable size for inducing ovulation.
• Theca cells can support bovine oocyte growth in vitro without the addition of steroid hormones
  Yang Y; Kanno C; Sakaguchi K; Katagiri S; Yanagawa Y; Nagano M
  Theriogenology, 142, 41, 47, 2020年01月, ［査読有り］, ［国際誌］
  英語, 研究論文（学術雑誌）, Theca cells (TCs) are essential to folliculogenesis by contributing to steroidogenesis. However, the in vitro growth (IVG) of oocytes co-cultured with TCs has not yet been examined. In the present study, we investigated the feasibility of the IVG of bovine oocyte-cumulus-granulosa cell complexes (OCGCs) co-cultured with TCs and the developmental competence of co-cultured oocytes. OCGCs and TCs were co-cultured without steroid hormone addition for 12 days. Steroidogenesis, the viability of OCGCs, and TC numbers during co-culture were assessed every 4 days. After IVG, oocytes were matured and the nuclear status was evaluated. Some oocytes were inseminated and cultured to examine blastocyst development. During the co-culture, androstenedione production by TCs was only observed during the first 4 days (1.1 ng/well) while estradiol-17β was continuously produced, peaking during the second 4 days (0.5 ng/well). The number of TCs decreased to ∼60% of the seeding number (4.0 × 104 cells/well) during the first 4 days, and was maintained thereafter. The majority of co-cultured OCGCs (82.7%) survived after 12-day IVG. Only a few OCGCs (6.2%) survived in the OCGC culture without TCs (p < 0.01); however, the addition of androstenedione to the culture medium markedly improved survivability to 80.1%, which was similar to that in the co-culture with TCs. In the subsequent development of oocytes derived from the co-culture, 58.3% reached metaphase II stage, 58.7% cleaved, and 17.3% developed to blastocysts, which were similar values to those of oocytes cultured with the addition of androstenedione. In conclusion, TC-produced androgen contributes to OCGC growth and the acquisition of subsequent embryonic developmental competence.
• Relationships between the antral follicle count, steroidogenesis, and secretion of follicle-stimulating hormone and anti-Müllerian hormone during follicular growth in cattle.
  Sakaguchi K; Yanagawa Y; Yoshioka K; Suda T; Katagiri S; Nagano M
  Reproductive biology and endocrinology : RB&E, 17, 1, 88, 88, 2019年11月, ［査読有り］, ［国際誌］
  英語, 研究論文（学術雑誌）, BACKGROUND: The antral follicle count (AFC) in mammalian ovaries positively correlates with female fertility. To clarify the causes of differences in fertility between low and high AFC cows, we investigated follicular growth dynamics and hormone concentrations in plasma, follicular fluid, and in vitro growth (IVG) media at different stages of follicular growth. METHODS: Seven cows were divided into high AFC (n = 4, > 30 follicles) and low AFC (n = 3, < 30 follicles) groups based on the peak AFC detected by ultrasonography. These cows were subjected to estrous synchronization, daily ovarian ultrasonography, and blood collection. Their follicular fluid was collected from dominant follicles at different stages (selection, luteal, and ovulatory phases). In another experiment, we cultured oocyte-cumulus-granulosa cell complexes collected from early antral follicles (< 1 mm) for 12 days. Estradiol-17β (E2), testosterone (T), progesterone (P4), and anti-Müllerian hormone (AMH) concentrations in follicular fluids and plasma were measured. Plasma follicle-stimulating hormone (FSH) concentrations were examined. E2, P4, and AMH concentrations were also measured in IVG media. RESULTS: The numbers of small (< 4 mm) and intermediate (4-8 mm) follicles were larger in the high AFC group than in the low AFC group (P < 0.05). The number of intermediate follicles was stable in the low AFC group, indicating consistent development. However, the number of these follicles fluctuated in the high AFC group. Plasma FSH concentrations were higher, whereas E2 and T concentrations were lower in the low AFC group (P < 0.05). E2 concentrations and the E2/P4 ratio in ovulatory follicles and IVG media on day 8 were higher in the high AFC group (P < 0.05). AMH concentrations in plasma and IVG media (P < 0.01) were higher in the high AFC group. CONCLUSIONS: The weaker response to FSH of granulosa cells caused low E2 production in the low AFC group, resulting in high FSH concentrations and the consistent development of intermediate follicles. Conversely, higher E2 concentrations suppressed FSH secretion in the high AFC group. Granulosa cells in the high AFC group had the ability to produce more AMH than those in the low AFC group throughout IVG culture.
• 若手研究者の描く獣医繁殖学の未来 牛子宮内膜厚の変化とその調節機序
  杉浦 智親; 奥山 みなみ; 中田 健; 片桐 成二
  日本獣医学会学術集会講演要旨集, 162回, 264, 264, (公社)日本獣医学会, 2019年08月, ［査読有り］
  日本語
• Monitoring follicular dynamics using ultrasonography in captive brown bears (Ursus arctos) during the breeding season
  Torii Y; Matsumoto N; Sakamoto H; Nagano M; Katagiri S; Yanagawa Y
  Theriogenology, 140, 164, 170, 2019年08月, ［査読有り］, ［国際誌］
  英語, 研究論文（学術雑誌）, Artificial insemination (AI) may be a useful tool in the reproductive management of endangered animals, including bears. To establish an AI program for bears, we investigated follicular dynamics using weekly transrectal ultrasonography in six captive brown bears. Along with ultrasonography, we monitored plasma progesterone (P4) and estradiol-17β (E2) concentrations. Furthermore, two bears were administered a gonadotropin releasing hormone (GnRH) agonist to induce ovulation on the first day on which the largest follicle reached more than 10.0 mm in diameter. Brown bears showed two patterns of follicular development in the early and late periods of the breeding season. In the early period (May to mid-June), multiple follicular waves were observed; namely, many follicles developed, and the largest follicles grew to less than 6.0 mm in diameter then regressed. In the late period (mid-June to July), one or two follicles grew to greater than 6.0 mm in diameter and developed as dominant follicles. Moreover, the growth rate of the largest follicle in the late period was faster than that in the early period of the breeding season. One bear with a follicle of 13.1 mm ovulated spontaneously, and one bear ovulated when the follicle was 10.2 mm in diameter after GnRH agonist treatment. Plasma E2 concentrations increased and showed peaks five to seven days before the largest follicles reached their maximum size. Plasma P4 concentrations increased on the day the corpus luteum could be detected using ultrasonography. This is the first study that showed there are two patterns of follicular development in brown bears. Furthermore, the largest follicle reaching greater than 10.0 mm in diameter could be an indicator of the appearance of ovulatory follicles.
• Effects of follicle-stimulating hormone followed by gonadotropin-releasing hormone on embryo production by ovum pick-up and in vitro fertilization in the river buffalo (Bubalus bubalis).
  Sakaguchi K; Maylem ERS; Tilwani RC; Yanagawa Y; Katagiri S; Atabay EC; Atabay EP; Nagano M
  Animal science journal = Nihon chikusan Gakkaiho, 90, 5, 690, 695, 2019年03月, ［査読有り］, ［国際誌］
  英語, 研究論文（学術雑誌）, In this study, we examined the effects of superstimulation using follicle-stimulating hormone (FSH) followed by gonadotropin-releasing hormone (GnRH) on buffalo embryo production by ultrasound-guided ovum pick-up (OPU) and in vitro fertilization (IVF). Nine Murrah buffaloes were subjected to OPU-IVF without superstimulation (control). The morphologies of the oocytes collected were evaluated, and oocytes were then submitted to in vitro maturation (IVM). Two days after OPU, same nine buffaloes were treated with twice-daily injections of FSH for 3 days for superstimulation followed by a GnRH injection. Oocytes were collected by OPU 23-24 hr after the GnRH injection and submitted to IVM (the superstimulated group). The total number of follicles, number of follicles with a diameter > 8 mm, and number of oocytes surrounded by multi-layered cumulus cells were higher in the superstimulated group than in the control group (p ≤ 0.05). After IVF, the percentages of cleavage and development to blastocysts were higher in the superstimulated group than in the control group (p < 0.05). In conclusion, superstimulation improved the quality of oocytes and the embryo productivity of OPU-IVF in river buffaloes.
• Astaxanthin improves the developmental competence of in vitro grown oocytes and modifies the steroidogenesis of granulosa cells derived from bovine early antral follicles
  Abdel-Ghani MA; Yanagawa Y; Balboula AZ; Sakaguchi K; Kanno C; Katagiri S; Takahashi M; Nagano M
  Reproduction, fertility and development, 31, 2, 272, 281, 2019年01月, ［査読有り］, ［国際誌］
  英語, 研究論文（学術雑誌）, In this study we investigated the effect of astaxanthin (Ax), which exhibits strong antioxidant activity, during invitro growth (IVG) on the developmental competence of oocytes and steroidogenesis of granulosa cells derived from early antral follicles. Bovine oocyte-cumulus-granulosa complexes collected from early antral follicles were cultured for 12 days in the presence or absence (control) of 500µM Ax. The viability of oocytes and antrum formation in the granulosa cell layer during IVG culture were greater in the presence than absence of Ax (P<0.05). Regardless of Ax treatment, 17β-oestradiol production increased during IVG culture; however, progesterone production was significantly lower in the presence than absence of Ax (P<0.05). Reactive oxygen species levels were lower in Ax-treated oocytes than in controls after IVG (P<0.05). Although nuclear maturation and cleavage rates did not differ between the Ax-treated and control groups, Ax treatment led to weaker cathepsin B activity in oocytes and better blastocyst rates than in controls (P<0.05). Accordingly, Ax treatment during IVG increased the total number of cells in blastocysts (P<0.05). These results indicate that Ax supplementation of IVG medium improves the quality of bovine oocytes due to its antioxidative effects on growing oocytes and its suppression of the luteinisation of granulosa cells.
• Relationship between the antral follicle count in bovine ovaries from a local abattoir and steroidogenesis of granulosa cells cultured as oocyte-cumulus-granulosa complexes.
  Sakaguchi K; Tanida T; Abdel-Ghani MA; Kanno C; Yanagawa Y; Katagiri S; Nagano M
  The Journal of reproduction and development, 64, 6, 503, 510, 2018年12月, ［査読有り］, ［国内誌］
  英語, 研究論文（学術雑誌）, The antral follicle count (AFC) is used as an indicator of cow fertility. We herein investigated the relationship between AFC and the steroidogenesis of granulosa cells and confirmed the developmental competence of oocytes derived from early antral follicles (0.5-1.0 mm) using in vitro growth culture. Slaughterhouse-derived ovaries were divided into high (≥ 25) and low (< 25) AFC groups based on AFC (≥ 2.0 mm). Oocyte-cumulus-granulosa complexes (OCGCs) collected from early antral follicles were cultured for 12 days. The total number, viability, and diameter of granulosa cells and estradiol-17β and progesterone production during the culture were evaluated. Surviving oocytes on day 12 were subjected to in vitro maturation, and their volume and nuclear status were evaluated. Some oocytes were subjected to the evaluation of developmental competence to blastocysts. Although the total number and viability of granulosa cells did not differ between the groups, granulosa cell diameters were smaller in the high AFC group than in the low AFC group. The estradiol-17β and progesterone ratio on day 8 was higher in the high AFC group than in the low AFC group. Oocyte volumes and nuclear maturation rates were greater in the high AFC group than in the low AFC group. The development rate to blastocysts was 9.1% in the high AFC group, while no oocytes developed to blastocysts in the low AFC group. Therefore, estradiol-17β production by granulosa cells appears to be greater in high AFC cattle than in low AFC cattle, thereby promoting the acquisition of oocyte competence.
• Effect of astaxanthin addition to an individual culture system for in vitro maturation of bovine oocytes on accumulation of reactive oxygen species and mitochondrial activity
  Erdenetogtokh P; Kanno C; Sakaguchi K; Yanagawa Y; Katagiri S; Nagano M
  Japanese Journal of Veterinary Research, 66, 4, 325, 329, 2018年11月, ［査読有り］
  英語, 研究論文（学術雑誌）
• 乳牛の人工授精時の子宮内膜厚と受胎性との関係
  杉浦 智親; 富永 翔太; 森好 政晴; 片桐 成二; 中田 健
  日本獣医学会学術集会講演要旨集, 161回, 406, 406, (公社)日本獣医学会, 2018年08月, ［査読有り］
  日本語
• Effect of a single epidural administration of follicle-stimulating hormone via caudal vertebrae on superstimulation for in vivo and in vitro embryo production in Japanese black cows.
  Sakaguchi K; Ideta A; Yanagawa Y; Nagano M; Katagiri S; Konishi M
  The Journal of reproduction and development, 64, 5, 451, 455, 2018年06月, ［査読有り］, ［国内誌］
  英語, 研究論文（学術雑誌）, Here, we describe a simplified procedure for embryo production in the Japanese black cow that uses a single caudal epidural injection of follicle-stimulating hormone (FSH). First, we compared the efficiency of superovulation for in vivo embryo production between conventional multiple FSH treatment (control, n = 10) and single epidural administration (epidural, n = 5). The number of transferable blastocysts was similar between control and epidural groups (4.7 ± 3.5 and 9.0 ± 6.0, respectively). Next, we compared in vitro embryo production by ovum pick-up and in vitro fertilization (OPU-IVF) between control (n = 12) and epidural groups (n = 12). The rate of development to transferable blastocysts was higher in the epidural group than in the control (23.3 vs. 10.5%, P < 0.001). In conclusion, a single epidural administration of FSH can induce follicular development comparable to that of the conventional superovulation protocol and may improve the productivity of OPU-IVF.
• Effects of pre-maturational culture duration on developmental competence of bovine small-sized oocytes.
  Abdel-Ghani MA; Sakaguchi K; Kanno C; Yanagawa Y; Katagiri S; Nagano M
  The Journal of reproduction and development, 64, 4, 365, 369, 2018年05月, ［査読有り］, ［国内誌］
  英語, 研究論文（学術雑誌）, We investigated the effects of pre-maturational (pre-IVM) culture on the developmental competence of small-sized bovine oocytes (110 and < 115 µm). Oocytes were cultured with 3-isobutyl-1-methylxanthine (IBMX) for 0, 5, or 10 h and subjected to in vitro maturation, fertilization, and culture. The cleavage rate (73%) of small-sized oocytes with 5 h pre-IVM was higher than those with 0 and 10 h pre-IVM (61 and 62%, respectively). The blastocyst rate (16%) of embryos derived from small-sized oocytes with 5 h pre-IVM was higher than those with 0 and 10 h pre-IVM (9 and 8%, respectively). In addition, small-sized oocytes with 5 h pre-IVM had a higher mean cell number in blastocysts (134.1 ± 34.8) than those with 0 and 10 h pre-IVM (100.2 ± 17.2 and 107.8 ± 23.7, respectively). In conclusion, the pre-IVM of small-sized oocytes with IBMX for 5 h improved the developmental competence of bovine oocytes, as well as the quality of blastocysts.
• Relationship between bovine endometrial thickness and plasma progesterone and estradiol concentrations in natural and induced estrus.
  Tomochika Sugiura; Shun Akiyoshi; Fumihiro Inoue; Yojiro Yanagawa; Masaharu Moriyoshi; Motoshi Tajima; Seiji Katagiri
  The Journal of reproduction and development, 64, 2, 135, 143, 2018年04月13日, ［査読有り］, ［国内誌］
  英語, 研究論文（学術雑誌）, The objective of this study was to investigate cyclical changes in endometrial thickness in relation to progesterone (P4) and estradiol-17β (E2) concentrations during natural and induced estrus in 15 cows. In the prostaglandin (PG) F2α-induced estrus group, ultrasonography (USG) at 6-h intervals was used to determine endometrial thickness 48-24 h before the PGF2α treatment until 24 h after ovulation (ovulation = Day 0). In the natural estrus group, USG was performed every 48 h from Day 3 to Days 15-18 after the first ovulation, and then every 6 h until 24 h after ovulation. Endometrial thickness was standardized using Day 13 as a reference day. Blood was collected during every USG examination and plasma P4 and E2 concentrations were determined. Endometrial thickness of the induced estrus group (n = 11) was greater than that of the natural estrus group (n = 9) between 60 and 12 h before ovulation (P < 0.05). In the natural estrus group, prior to an increase in endometrial thickness, a decrease in P4 and an increase in E2 were detected. In the induced estrus group, based on the time of ovulation, an increase in endometrial thickness was detected at the same time of a decrease in P4 before an increase in E2. These results suggest that decreases in P4 concentrations may be a cue to changes in endometrial thickness, while increases in E2 concentrations appear to sustain and/or enhance these changes.
• Evaluation of the chemiluminescent enzyme immunoassay system for the measurement of testosterone in the serum and whole blood of stallions
  Toishi Y; Tsunoda N; Nagata SI; Kirisawa R; Nagaoka K; Watanabe G; Yanagawa Y; Katagiri S; Taya K
  J Reprod Dev., 64, 1, 41, 47, 2018年02月, ［査読有り］, ［国内誌］
  英語, 研究論文（学術雑誌）, Testosterone (T) concentration is a useful indicator of reproductive function in male animals. However, T concentration is not usually measured in veterinary clinics, partly due to the unavailability of reliable and rapid assays for animal samples. In this study, a rapid chemiluminescent enzyme immunoassay system (CLEIA system) that was developed for the measurement of T concentration in humans use was validated for stallion blood samples. First, serum T concentrations were measured using the CLEIA system and compared with those measured by a fluoroimmunoassay that has been validated for use in stallions. The serum T concentrations measured by the two methods were highly correlated (r = 0.9865, n = 56). Second, to validate the use of whole blood as assay samples, T concentrations in whole blood and in the serum were measured by the CLEIA system. T concentrations in both samples were highly correlated (r = 0.9665, n = 64). Finally, to evaluate the practical value of the CLEIA system in clinical settings, T concentrations were measured in three stallions with reproductive abnormalities after the administration of human chorionic gonadotropin (hCG). Two stallions with small or absent testes in the scrotum showed an increase in T production in response to hCG administration and one stallion with seminoma did not. In conclusion, the CLEIA system was found to be a rapid and reliable tool for measuring T concentrations in stallions and may improve reproductive management in clinical settings and in breeding studs.
• A transvaginal endoscopy-based technique for performing ovarian examinations in sows
  Minami W. Okuyama; Tomochika Sugiura; Masaharu Moriyoshi; Kazuto Yamashita; Jun Tamura; Seiji Katagiri
  JOURNAL OF REPRODUCTION AND DEVELOPMENT, 63, 6, 617, 622, 2017年12月, ［査読有り］, ［最終著者, 責任著者］
  英語, 研究論文（学術雑誌）
• Extension of the culture period for the in vitro growth of bovine oocytes in the presence of bone morphogenetic protein-4 increases oocyte diameter, but impairs subsequent developmental competence
  Yang Y; Kanno C; Sakaguchi K; Yanagawa Y; Katagiri S; Nagano M
  Animal Science Journal, 88, 11, 1686, 1691, 2017年11月, ［査読有り］, ［国際誌］
  英語, 研究論文（学術雑誌）, Bone morphogenetic protein-4 (BMP-4) inhibits luteinization of granulosa cells during in vitro growth (IVG) culture of bovine oocytes; however, oocytes derived from a 12 day IVG were less competent for development than in vivo-grown oocytes. We herein investigated whether an extended IVG culture with BMP-4 improves oocyte growth and development to blastocysts after in vitro fertilization. Oocyte-granulosa cell complexes (OGCs) were cultured for 14 or 16 days with BMP-4 (10 ng/mL), while a 12 day culture with BMP-4 served as the in vitro control. OGC viability was maintained for the 16 day culture with BMP-4 (83.2%), but was significantly lower without BMP-4 (58.9%) than the control (83.0%). Prolong-cultured oocytes at 16 days had statistically greater diameter (114.6 μm) than the control (111.7 μm). IVG oocytes with BMP-4 for the 16 day culture had a similar nuclear maturation rate to the control (approximately 67%); however, blastocyst rates in BMP-4 treated oocytes of 14 (1.8%) and 16 day (0%) IVG were statistically lower than that of 12 day IVG (9.0%). In conclusion, BMP-4 maintained OGC viability and promoted oocyte growth in a prolonged culture, but impaired the developmental competence of oocytes. Prolonged culture may not be an appropriate strategy for enhancing the developmental competence of IVG oocytes.
• Comparison of sperm subpopulation structures in first and second ejaculated semen from Japanese black bulls by a cluster analysis of sperm motility evaluated by a CASA system
  Kanno C; Sakamoto KQ; Yanagawa Y; Takahashi Y; Katagiri S; Nagano M
  The Journal of Veterinary Medical Science, 79, 8, 1359, 1365, 公益社団法人 日本獣医学会, 2017年06月, ［査読有り］
  英語, 研究論文（学術雑誌）,

  In the present study, bull sperm in the first and second ejaculates were divided into subpopulations based on their motility characteristics using a cluster analysis of data from computer-assisted sperm motility analysis (CASA). Semen samples were collected from 4 Japanese black bulls. Data from 9,228 motile sperm were classified into 4 clusters; 1) very rapid and progressively motile sperm, 2) rapid and circularly motile sperm with widely moving heads, 3) moderately motile sperm with heads moving frequently in a short length, and 4) poorly motile sperm. The percentage of cluster 1 varied between bulls. The first ejaculates had a higher proportion of cluster 2 and lower proportion of cluster 3 than the second ejaculates.

• Effects of semen preservation procedure in egg yolk-tris based extender on bull spermatozoa characteristics
  Kanno C; Yanagawa Y; Takahashi Y; Katagiri S; Nagano M
  Japanese Journal of Veterinary Research, 65, 3, 151, 157, Faculty of Veterinary Medicine, Hokkaido University, 2017年05月, ［査読有り］
  英語, 研究論文（学術雑誌）, To verify the dynamics of damages to spermatozoa during semen freezing, characteristics of spermatozoa collected from 3 Japanese black bulls were evaluated by using fluorescent staining. Pre-diluted sample showed the highest proportion of spermatozoa with intact plasma membrane, intact acrosome and high mitochondrial potential. The proportion of spermatozoa with intact plasma membrane, intact acrosome, and low mitochondrial membrane potential were higher after cooling to 4°C than the other processes. During cooling preservation examined in this study, the proportion of spermatozoa with damaged acrosome increased. These results lead us to speculate that, during cooling process, spermatozoa may be firstly injured to mitochondrial membrane, and low mitochondrial function may cause the impairment of plasma membrane and subsequent cell death with acrosomal damage.
• Early germinal vesicle breakdown is a predictor of high preimplantation developmental competent oocytes in mice.
  Higaki S; Kishi M; Koyama K; Nagano M; Katagiri S; Takada T; Takahashi Y
  Zygote (Cambridge, England), 25, 1, 41, 48, 2017年02月, ［査読有り］
• Endometrial epidermal growth factor profile and its abnormalities in dairy cows
  Katagiri Seiji; Moriyoshi Masaharu; Yanagawa Yojiro
  JOURNAL OF REPRODUCTION AND DEVELOPMENT, 62, 5, 465, 470, 2016年10月, ［査読有り］, ［筆頭著者, 責任著者］, ［国内誌］
  英語, 研究論文（学術雑誌）
• 北海道内における乳牛への性選別精液使用が後継牛生産と母牛の生存率に与える影響
  菅野 智裕; 萩原 精一; 伊藤 純一; 廣田 和久; 片桐 成二; 永野 昌志
  北海道獣医師会雑誌, 60, 8, 378, 378, (公社)北海道獣医師会, 2016年08月, ［査読有り］
  日本語
• 北海道における乳牛への性選別乳牛精液の使用が産子の性別及び母牛の生存率に及ぼす影響
  萩原 精一; 菅野 智裕; 伊藤 純一; 廣田 和久; 永野 昌志; 片桐 成二
  日本獣医師会雑誌, 69, 7, 383, 388, (公社)日本獣医師会, 2016年07月, ［査読有り］
  日本語
• The relationship between antral follicle count in a bovine ovary and developmental competence of in vitro-grown oocytes derived from early antral follicles.
  Nagai K; Yanagawa Y; Katagiri S; Nagano M
  Biomedical research (Tokyo, Japan), 37, 1, 63, 71, 2016年, ［査読有り］, ［国内誌］
  英語, 研究論文（学術雑誌）, To clarify the relationship between ovarian reserve and the developmental competence of bovine oocytes, oocyte-granulosa complexes (OGCs) collected from early antral follicles (≤ 1 mm) in ovaries with high (≥ 25) and low (<25) antral follicle counts (AFCs) were used. OGCs derived from different AFC groups were cultured for growth followed by maturation, fertilization and blastocyst formation. Viability of OGCs during growth culture was similar between groups; however, OGCs in the high-AFC group had a larger number of granulosa cells than the low-AFC group at 12 days of growth. The proportion of matured oocytes in the high-AFC group was higher than that in the low-AFC group. Mitochondrial activity of oocytes before maturation in the high-AFC group was higher than that in the low-AFC group; however, accumulation of reactive oxygen species was similar between groups. Cleavage rate in the high-AFC group tended to be higher than that in the low-AFC group, although blastocyst development was similar between groups. In conclusion, oocytes derived from ovaries with high AFC have higher maturational ability and fertilizability than those from low AFC. The difference may be caused by high proliferation of granulosa cells from ovaries with high AFC.
• 個別管理培養ディッシュを用いた牛体外受精胚の培養個数が胚の発生率に与える影響
  高山茉莉; 片桐成二; 片桐成二; 森好政晴; 堂地修; 今井敬
  繁殖技術, 35, 3, 59, 61, 北海道家畜人工授精師協会, 2015年12月, ［査読有り］
  日本語
• Fertilizability of oocytes derived from Holstein cows having different antral follicle counts in ovaries.
  Nagai K; Yanagawa Y; Katagiri S; Nagano M
  Animal reproduction science, 163, 172, 178, 2015年12月, ［査読有り］, ［国際誌］
  英語, 研究論文（学術雑誌）, In this study, to clarify the relationship between ovarian reserve and oocyte quality, cumulus-oocyte complexes (COCs) were collected repeatedly by ovum pick-up (OPU) from cows with high and low antral follicle counts (AFCs) at short (3-4 days) and long (7 days) intervals, and COC morphologies and oocyte fertilizability were examined. The relationship between AFC and follicular growth after OPU was also investigated. Cows showing AFC of ≥30 in at least one OPU session were grouped into the high-AFC group. At a short interval, follicular sizes and COC morphologies were similar between the different AFC groups. However, the normal fertilization rate was higher in the high-AFC group than in the low one, although total penetration rates were similar. At a long interval, the percentage of COCs with poor morphology in the high-AFC group was higher and the normal fertilization rate was lower than in the low one. In the low-AFC group, normal fertilization rates at short and long intervals were similar, and mean follicular size became larger at a long than at a short interval. However, mean follicular sizes at short- and long-interval OPU were similar in the high-AFC group. In conclusion, it is suggested that oocytes derived from cows with high AFC had higher fertilizability than those from cows with low AFC when OPUs were performed at a short (3-4 days) interval. However, oocyte quality in high-AFC cows was impaired by long-interval (7 days) OPU, possibly due to the degradation of follicles.
• 乳牛の子宮における上皮成長因子発現の異常による受胎性低下とその対策
  片桐 成二
  繁殖技術 = Technic for animal reproduction, 34, 4, 50, 53, 北海道家畜人工授精師協会, 2015年03月, ［査読有り］
  日本語
• 分娩後のホルスタイン種への黒毛和種精漿の投与効果
  板橋知子; 片桐成二; 柳川洋二郎; 佐藤秀俊; 及川俊徳
  宮城県獣医師会会報, 68, 1, 13‐15, 2015年01月, ［査読有り］
  日本語, 研究論文（大学，研究機関等紀要）
• Accessory corpora lutea formation in pregnant Hokkaido sika deer (Cervus nippon yesoensis) investigated by examination of ovarian dynamics and steroid hormone concentrations.
  Yanagawa Y; Matsuura Y; Suzuki M; Saga S; Okuyama H; Fukui D; Bando G; Nagano M; Katagiri S; Takahashi Y; Tsubota T
  The Journal of reproduction and development, 61, 1, 61, 66, 2015年, ［査読有り］
  英語, 研究論文（学術雑誌）
• ホルスタイン種リピートブリーダー牛に対する黒毛和種精漿注入の効果
  板橋 知子; 片桐 成二; 柳川 洋二郎; 及川 俊徳
  東北農業研究, 67, 75, 76, [東北農業試験研究協議会], 2014年12月, ［査読有り］
  日本語, 乳牛では受胎率の低下が問題となっており、その原因の一つとして子宮内膜における上皮成長因子(EGF)の発現異常が高産乳牛やリピートブリーダーで確認されている。正常牛の子宮内膜EGF濃度は、発情2～4日目および13～14日目に上昇し二峰性のピークを示すが、リピートブリーダー牛ではこのピークが低下し、周期的変動が消失することが報告されている。最近、牛精漿をリピートブリーダー牛の膣内に注入することによって子宮内膜のEGF発現が正常化し、受胎性が向上したとの報告がある。そこで今回は、場内で繋養している黒毛和種種雄牛の精漿をホルスタイン種リピートブリーダー牛に投与し、その効果について検討した。
• Effects of ovarian storage condition on in vitro maturation of Hokkaido sika deer (Cervus nippon yesoensis) oocytes
  Tulake Kuerban; Yanagawa Yojiro; Takahashi Yoshiyuki; Katagiri Seiji; Higaki Shogo; Koyama Keisuke; Wang Xuguang; Li Heping
  JAPANESE JOURNAL OF VETERINARY RESEARCH, 62, 4, 187, 192, 2014年11月, ［査読有り］, ［国内誌］
  英語, 研究論文（学術雑誌）
• Cryopreservation of zebrafish (Danio rerio) primordial germ cells by vitrification of yolk-intact and yolk-depleted embryos using various cryoprotectant solutions.
  Higaki S; Kawakami Y; Eto Y; Yamaha E; Nagano M; Katagiri S; Takada T; Takahashi Y
  Cryobiology, 67, 374, 382, 3, 2013年12月, ［査読有り］
• Effects of parity and litter size on the energy contents and immunoglobulin G concentrations of Awassi ewe colostrum
  HIGAKI SHOGO; NAGANO MASASHI; KATAGIRI SEIJI; TAKAHASHI YOSHIYUKI
  Turkish Journal of Veterinary and Animal Sciences, 37, 1, 109, 112, TÜBİTAK, 2013年02月, ［査読有り］
  英語, This study determined the energy content and immunoglobulin G (IgG) concentration of Awassi ewe colostrum and examined the effects of parity and litter size on them. Colostral samples were collected from 57 ewes from the 1st to 7th parities with a litter size of 1 or 2, within 12 h after lambing. Concentrations of colostral fat, lactose, and protein were measured as energy sources, and IgG was measured as representative of the immunoglobulin content of the colostrum. Mean values obtained from analyses of the ewe colostrum samples were 7.4±2.1 kJ/g for the energy value and 60.9±21.4 mg/mL for IgG. Ewe parity did not influence colostral energy content, whereas the IgG concentration of the colostrum obtained from the primiparous ewes was higher than that from the multiparous ewes (P < 0.05). Among the multiparous ewes, the colostrum obtained from ewes carrying twins showed higher energy content and IgG concentrations than that from those carrying a single lamb (P < 0.05).
• 精漿成分による牛の子宮機能調節
  片桐 成二
  日本胚移植学雑誌 = Japanese journal of embryo transfer, 35, 1, 21, 24, 2013年01月21日, ［査読有り］
  日本語
• Alteration of the Endometrial EGF Profile as a Potential Mechanism Connecting the Alterations in the Ovarian Steroid Hormone Profile to Embryonic Loss in Repeat Breeders and High-producing Cows
  KATAGIRI Seiji; MORIYOSHI Masaharu
  Journal of Reproduction and Development, 59, 5, 415, 420, THE SOCIETY FOR REPRODUCTION AND DEVELOPMENT, 2013年, ［査読有り］, ［国内誌］
  英語, 研究論文（学術雑誌）, Poor reproductive efficiency is a worldwide problem that has affected the dairy industry during the last several decades. In an attempt to explain the changes in reproductive physiology caused by high milk production, a model of elevated steroid metabolism in lactating dairy cows has been proposed. A slow increase in levels and low peak levels of estradiol (E₂) and progesterone (P₄) characterize endocrine changes in high producing cows. Similar changes have been reported in the repeat breeder cows. The abnormal changes in E₂ and P₄ concentrations of these cows may cause an improper uterine environment due to disturbed expression of growth factors and cytokines in the endometrium. This review focuses on the alteration in epidermal growth factor (EGF) profile in the endometrium during the estrous cycle. The normal cow has two peaks of EGF concentrations on days 2–4 and 13–14. Low concentrations of EGF on these days distinguished both high-producing and repeat breeder cows from normal cows. Alteration of the EGF profile could be found in 70 and 40% of the repeat breeder and high-producing cows, respectively. Treatment with a high dose of estradiol benzoate and an intravaginal progesterone-releasing device restored the normal EGF profile in about 70% of the affected cows. The cows having a normal EGF profile after treatment showed a higher pregnancy rate than the cows with the altered profile. Further studies to understand the etiology of the alteration in the EGF profile are needed to develop another treatment option and preventive management for this problem.
• Low Incidence of an Altered Endometrial Epidermal Growth Factor (EGF) Profile in Repeat Breeder Holstein Heifers and Differential Effect of Parity on the EGF Profile Between Fertile Holstein (Dairy) and Japanese Black (Beef) Cattle
  KATAGIRI Seiji; MORIYOSHI Masaharu; TAKAHASHI Yoshiyuki
  Journal of Reproduction and Development, 59, 6, 575, 579, THE SOCIETY FOR REPRODUCTION AND DEVELOPMENT, 2013年, ［査読有り］, ［国内誌］
  英語, 研究論文（学術雑誌）, A high incidence (about 70%) of alteration in endometrial epidermal growth factor (EGF) profile, i.e., loss of 2 peaks on days 2–4 and 13–14, has been linked to a reduced fertility in multiparous repeat breeder Holstein cows. However, the EGF profile in Holstein heifers and other breeds (types) of cattle has not been investigated. In study 1, EGF concentrations were determined using endometrial tissues obtained by biopsy on days 3, 7 and 14 from 84 fertile Holstein heifers to obtain a normal range and 53 repeat breeder Holstein heifers to estimate incidence of alterations in the EGF profile. In repeat breeder heifers, EGF concentrations were similar to fertile controls on 3 days and five animals (9.4%) had an altered EGF profile with EGF concentrations below the normal range on days 3 and 14. In study 2, EGF concentrations on day 3 were repeatedly examined from the nulliparous period to the third postpartum period in 28 Holstein (dairy) and 47 Japanese Black (beef) cattle. The effect of parity on EGF concentrations on day 3 was different between Holstein and Japanese Black cattle. In Japanese Black cows, the EGF concentrations were consistently high throughout the study period, while in Holstein cows, the EGF concentrations decreased after the second calving. In conclusion, unlike multiparous repeat breeder Holstein cows, an altered EGF profile may not be a major cause of repeat breeding in Holstein heifers, and the peak EGF concentrations around day 3 may decrease even in fertile populations of multiparous dairy cows, but not in beef cows.
• Cryopreservation of Primordial Germ Cells by Rapid Cooling of Whole Zebrafish (Danio rerio) Embryos
  Shogo Higaki; Kentaro Mochizuki; Yuichiro Akashi; Etsuro Yamaha; Seiji Katagiri; Yoshiyuki Takahashi
  JOURNAL OF REPRODUCTION AND DEVELOPMENT, 56, 2, 212, 218, 2010年04月, ［査読有り］
  英語, 研究論文（学術雑誌）
• Production of fertile zebrafish (Danio rerio) possessing germ cells (gametes) originated from primordial germ cells recovered from vitrified embryos.
  Higaki S; Eto Y; Kawakami Y; Yamaha E; Kagawa N; Kuwayama M; Nagano M; Katagiri S; Takahashi Y
  Reproduction (Cambridge, England), 139, 733, 740, 4, 2010年04月, ［査読有り］
• Measurement of pO2 in cultured mouse oocytes using electron paramagnetic resonance oximetry.
  Higaki S; Fujii H; Nagano M; Katagiri S; Takahashi Y
  Biomedical research (Tokyo, Japan), 31, 2, 165, 168, 2, 2010年04月, ［査読有り］
• Feasibility of cryopreservation of zebrafish (Danio rerio) primordial germ cells by whole embryo freezing
  Shogo Higaki; Kentaro Mochizuki; Hiroko Baba; Yuichiro Akashi; Etsuro Yamaha; Seiji Katagiri; Yoshiyuki Takahashi
  JAPANESE JOURNAL OF VETERINARY RESEARCH, 57, 2, 119, 128, 2009年08月, ［査読有り］
  英語, 研究論文（学術雑誌）
• Fetal Age Estimation of Hokkaido Sika Deer (Cervus nippon yesoensis) Using Ultrasonography During Early Pregnancy
  Yanagawa Yojiro; Matsuura Yukiko; Suzuki Masatsugu; Saga Shin-ichi; Okuyama Hideto; Fukui Daisuke; Bandou Gen; Katagiri Seiji; Takahashi Yoshiyuki; Tsubota Toshio
  JOURNAL OF REPRODUCTION AND DEVELOPMENT, 55, 2, 143, 148, 2009年04月, ［査読有り］
  英語, 研究論文（学術雑誌）
• A Progestin-Based Treatment with a High Dose of Estradiol Benzoate Normalizes Cyclic Changes in Endometrial EGF Concentrations and Restores Fertility in Repeat Breeder Cows
  Katagiri Seiji; Takahashi Yoshiyuki
  The Journal of reproduction and development, 54, 6, 473, 479, THE SOCIETY FOR REPRODUCTION AND DEVELOPMENT, 2008年12月01日, ［査読有り］, ［国内誌］
  英語, 研究論文（学術雑誌）, The objective of the present study was to examine the efficacy of a progestin-based treatment with a high dose of estradiol benzoate (EB) to normalize the epidermal growth factor (EGF) profile in the uterine endometrium and restore fertility in repeat breeder cows. Repeat breeder cows without peaks in their endometrial EGF concentrations on Days 3 and 14 of the estrous cycle were used throughout the study. The effect of 1 (standard dose), 2.5 and 5 mg of EB in a progestin-based treatment protocol (EB1, EB2.5 and EB5 treatments, respectively; n=5 for each group) on endometrial EGF concentrations was first examined. The EB1 and EB2.5 treatments in the repeat breeder cows produced a suppressed response in endometrial EGF compared with EB1 treatment in the fertile controls (n=5) and failed to restore the normal EGF profile during the next estrous cycle. However, EB5 treatment produced an increase in EGF concentrations similar to the fertile controls and normalized the endometrial EGF profile. The effects of the EB1 and EB5 treatments (n=30 for each group) on the endometrial EGF profile and fertility were then examined in the repeat breeder cows. The proportion of cows, with an EGF profile normalized by the treatments was higher in the EB5 group (66.7%) than in the EB1 (30.0%) and untreated control (13.3%; n=30) groups (P<0.01). The pregnancy rates of the cows having a normal EGF profile after treatment in the EB1 and EB5 groups were similar (88.9 and 85.0%, respectively) and higher than those of the cows having an abnormal profile within the same groups (19.0 and 30.0%, respectively, P<0.01). In summary, the endometrial response to EB in terms of the EGF concentration was suppressed in repeat breeder cows. A high dose (5 mg) of EB in a progestin-based treatment was found to be effective for restoration of a normal EGF profile and fertility in repeat breeder cows having lesser endometrial EGF concentrations on Days 3 and 14.
  
• Immunohistochemical localization of the estrogen receptor alpha (ERα) and progesterone receptor (PR) in the uterus of sika deer (Cervus nippon) during pregnancy
  Yanagawa Yojiro; Matsuura Yukiko; Suzuki Masatsugu; Katagiri Seiji; Tsubota Toshio
  Japanese Journal of Veterinary Research, 56, 3, 139, 149, The Graduate School of Veterinary Medicine, Hokkaido University, 2008年11月, ［査読有り］, ［国内誌］
  英語, 研究論文（学術雑誌）, Information on steroid hormone receptor distribution in the uterus is essential to understand the roles of their ligands in pregnancy. This study examined the spatio-temporal localization of estrogen receptor alpha (ERα) and progesterone receptor (PR) in the uterus of sika deer (Cervus nippon) to determine the estrogen and progesterone action site during pregnancy. Ovaries and uteri were collected from 21 pregnant sika deer with single fetus and two corpora lutea, ranging from Day 20 to Day 207 of pregnancy. In addition, genital organs were also collected from three sika deer whose gestatio...
• Rapid sex chromosomal chimerism analysis in heterosexual twin female calves by Loop-mediated Isothermal Amplification
  Hiroki Hirayama; Seiji Katagiri; Soichi Kageyama; Akira Minamihashi; Satoru Moriyasu; Ken Sawai; Sadao Onoe; Yoshiyuki Takahashi
  ANIMAL REPRODUCTION SCIENCE, 101, 1-2, 38, 44, 2007年09月, ［査読有り］
  英語, 研究論文（学術雑誌）
• The relationship between oocyte morphology and ovarian status in cattle.
  Nagano M; Hishinuma M; Katagiri S; Takahashi Y
  The Journal of reproduction and development, 53, 4, 953, 958, 4, 2007年08月, ［査読有り］
  英語, We investigated the relationships between oocyte morphology, follicular size and follicular waves using bovine ovaries derived from local abattoirs. Ovaries at the recruitment and selection phases contained larger numbers of oocytes with good developmental ability, although ovaries at the recruitment phase contained the largest numbers of follicles compared with ovaries at the selection and dominant phases. Dominant phase ovaries contained a high percentage of oocytes with as good developmental ability as selection phase ovaries; however, they contained the lowest total number of oocytes with good developmental ability. Small follicles under 3.0 mm in diameter contained large numbers of small and degenerating oocytes. In contrast, follicles more than 3.0 mm in diameter contained a higher percentage of oocytes with good developmental ability.
  
• Effects of isolation method and pre-treatment with ethylene glycol or raffinose before vitrification on in vitro viability of mouse preantral follicles.
  Nagano M; Atabay EP; Atabay EC; Hishinuma M; Katagiri S; Takahashi Y
  Biomedical research (Tokyo, Japan), 28, 3, 153, 160, 3, 2007年06月, ［査読有り］
  英語, Effects of isolation and vitrification protocols on follicular survival after warming were examined. Mouse preantral follicles enzymatically or mechanically isolated from ovaries of 12-day-old mice were exposed either to 2 M ethylene glycol (EG) for 2 or 5 min, or to ascending concentrations (0.15 then 0.3 M) of raffinose for 2 or 5 min each (2-2 and 5-5 min). They were then exposed to a vitrification solution (VS) composed of 6 M EG and 0.3 M raffinose for 0.5, 1, or 2 min before vitrification. Mechanically isolated follicles showed higher survival than enzymatically isolated follicles, regardless of periods of exposure to EG or raffinose and subsequent exposure to VS. After 10 days of culture, follicular growth and maturational ability of oocytes derived from vitrified follicles exposed to 2 M EG for 5 min and to VS for 1 min were higher than those from follicles exposed to raffinose solutions for 2-2 min and to VS for 1 min. Histological evaluation revealed that exposure of preantral follicles to raffinose solutions caused cytoplasmic vacuolation in granulosa cells which could be due to cellular shrinkage during dehydration; whereas, exposure to 2 M EG induced morphological alterations in follicles only to a lesser extent.
• ATP content and maturational/developmental ability of bovine oocytes with various cytoplasmic morphologies.
  Nagano M; Katagiri S; Takahashi Y
  Zygote (Cambridge, England), 14, 4, 299, 304, 4, 2006年11月, ［査読有り］
  英語, We examined the relationship among morphological appearance (six groups) of bovine oocytes, ATP content and maturational/developmental ability. Oocytes with a brown ooplasm (with or without a dark region) had intermediate levels of ATP at the germinal vesicle (GV) stage and showed higher rates of first polar body (PB) extrusion than the other groups. Oocytes with a low level of ATP (oocytes with a pale ooplasm without dark clusters) and oocytes with a high level of ATP (oocytes with a black ooplasm) showed lower rates of PB extrusion. During in vitro maturation, ATP levels in oocytes decreased at around GV breakdown and increased toward metaphase II (MII). MII oocytes having a brown ooplasm with a dark region, which had good developmental capacity, had a relatively high level of ATP. MII oocytes with a brown or pale ooplasm without dark clusters, which had poor developmental capacity, had low ATP levels. MII oocytes with a black ooplasm, which had poor developmental capacity, had an unusually high level of ATP. These results suggest that the morphological appearance of bovine oocytes is closely related to their ATP levels and that cytoplasmic morphology will give an advantage for the selection of oocytes with a high maturational and developmental ability.
• Potential relationship between normalization of endometrial epidermal growth factor profile and restoration of fertility in repeat breeder cows.
  Seiji Katagiri; Yoshiyuki Takahashi
  Animal reproduction science, 95, 1-2, 54, 66, 2006年09月, ［査読有り］, ［国際誌］
  英語, 研究論文（学術雑誌）, The present study characterized alterations of the endometrial epidermal growth factor (EGF) and examined potential relationships between normalization of the EGF and restoration of fertility in repeat breeder cows. In Experiment 1, endometrial tissues were obtained by biopsy on Days 3, 7 and 14 of the estrous cycle from 99 fertile dairy cows and normal ranges of uterine tissue EGF concentrations were determined. Then, eight fertile cows were examined for endometrial EGF concentrations on Days 3, 7 and 14 during the three consecutive estrous cycles. All eight cows had a normal EGF profile (EGF concentrations were within the normal ranges of all 3 days) in all three estrous cycles and endometrial EGF concentrations were similar among the three estrous cycles. In Experiment 2, 61 repeat breeder cows were examined EGF profile and 43 (70.5%) cows had altered EGF profiles compared with control profiles. A typical alteration was characterized by decreased concentrations on Days 3 and 14 and accounted for 86.0% of all alterations. When repeat breeder cows with altered EGF profiles (n=17) were left untreated, abnormality persisted in 14 (82.4%) cows at the second examination and only 3 animals became pregnant within the next two estrous cycles. Among 15 cows showing a typical alteration at the first examination, 11 (73.3%) cows had the same alteration until the third examination performed after two infertile inseminations following the second examination. When repeat breeder cows with altered EGF profiles (n=26) were given one of four therapeutic treatments, cows in which the EGF profile normalized after treatment had a greater pregnancy rate than those with altered profiles (11/14 animals versus 3/12 animals pregnant; P<0.05). In conclusion, suppressed endometrial EGF concentrations on Days 3 and 14 may be common alterations and persist between estrous cycles in repeat breeder cows. Potential relationship between normalization of the endometrial EGF profile and restoration of fertility was observed. Additional study to confirm results of the treatment is, however, necessary because the present study used a limited number of animals. Nevertheless, current data suggest that normalization of the EGF profile is one of the prerequisite factors to restore fertility.
• Relationship between bovine oocyte morphology and in vitro developmental potential.
  Nagano M; Katagiri S; Takahashi Y
  Zygote (Cambridge, England), 14, 53, 61, 1, 2006年02月, ［査読有り］
• Sucrose-exposed chemically enucleated mouse oocytes support blactocyst development of reconstituted embryos.
  ELSHEIKH Adil Salim; TAKAHASHI Yoshiyuki; KATAGIRI Seiji; KANAGAWA Hiroshi
  Reprod Fert Dev, 18, 6, 697, 701, 2006年, ［査読有り］
• 乳用牛における分娩後の卵胞発育ウェーブの発現時期と分娩前後のFSH分泌動態
  笹本 良彦; 坂口 実; 片桐 成二; 中田 健; 高橋 芳幸
  The Journal of Reproduction and Development, 50, Suppl., j79, j79, (公社)日本繁殖生物学会, 2004年08月, ［査読有り］
  日本語
• Changes in EGF concentrations during estrous cycle in bovine endometrium and their alterations in repeat breeder cows.
  Seiji Katagiri; Yoshiyuki Takahashi
  Theriogenology, 62, 1-2, 103, 12, 2004年07月, ［査読有り］, ［国際誌］
  英語, 研究論文（学術雑誌）, The objective of the present study was to determine if abnormalities in the cyclic changes of endometrial EGF concentrations can be a diagnostic tool for repeat breeder cows. First, the profile of EGF concentrations during the estrous cycle was determined using endometrial tissues obtained from 31 Holstein cows after slaughter. Cyclic cows had two peaks of EGF concentrations. Then, endometrial tissues were obtained from 12 control and 20 repeat breeder cows by biopsy on Days 3, 7, and 14 of the same estrous cycle. Endometrial EGF concentrations in biopsied samples of the controls were similar to those found in slaughterhouse materials; they were high on Days 3 and 14 (9.2 and 10.4 ng/g tissue, respectively) and low on Day 7 (3.8 ng/g tissue). Concentrations of EGF in repeat breeder cows had a different profile; they were similar on Days 3, 7, and 14 (4.4, 3.4, and 4.0 ng/g tissue, respectively). In conclusion, changes in endometrial EGF concentrations were altered in repeat breeders; these alterations may be a potential diagnostic marker for repeat breeder cows.
• Serum Leptin Levels during the Periparturient Period in Cows
  SOLIMAN Mohamed; ISHIOKA Katsumi; YOSHIDA Ryusuke; KOMABAYASHI Kenichi; HATAI Hitoshi; MATSUI Yoshitaka; HIRAI Tuneo; KATAGIRI Seiji; TAKAHASHI Yoshiyuki; KAWAKITA Yumi; ABE Hiroyuki; KITAMURA Hiroshi; KIMURA Kazuhiro; SAITO Masayuki
  The journal of veterinary medical science, 64, 11, 1053, 1056, JAPANESE SOCIETY OF VETERINARY SCIENCE, 2002年11月25日, ［査読有り］
  英語, Serum leptin concentrations were measured in antenatal and postnatal cows housed at two different locations. The mean serum leptin concentration was 9.2 ± 0.6 ng/m l (n=22) in one group, and was slightly lower in the other (7.4 ± 0.4 ng/ml, n=54), probably because of the different nutritional conditions between the two groups. There was no consistent variation in relation to the menstrual cycle and the periparturient period in both groups. Moreover, serum leptin concentrations during the periparturient period were independent of the number of delivery and the incidence of mastitis and milk fever. These results are quite different from those in rodents and human, suggesting the different regulatory mechanism of circulating leptin concentration in cows.
  
• Steroid Hormones Do Not Reactivate Neospora caninum in Ovariectomized Mice.
  KOBAYASHI Atsushi; KATAGIRI Seiji; KIMURA Takashi; OCHIAI Kenji; UMEMURA Takashi
  Journal of Veterinary Medical Science, 64, 9, 773, 777, JAPANESE SOCIETY OF VETERINARY SCIENCE, 2002年, ［査読有り］
  英語, The direct effects of three steroid hormones (progesterone, estradiol-17β and corticosterone) on the growth of Neospora caninum (N. caninum) tachyzoite were examined in Vero cells. Subsequently, ovariectomized BALB/c mice infected with N. caninum were treated with physiological concentrations of the steroid hormones for 1 or 2 weeks. These hormones had no direct effect on the parasite growth in vitro. In the infected mice, there was no significant difference in the parasite distribution and histopathological changes between the hormone-injected and control groups. No mice showed parasitemia at the time of autopsy. These results suggest that physiological levels of steroid hormones (progesterone, estradiol-17β and corticosterone) do not reactivate N. caninum in mice.
• In vitro viability of mouse oocytes vitrified in an ethylene glycol-based solution
  BAUTISTA Jose Arceo N.; DELA PENA Eufrocina C.; KATAGIRI Seiji; TAKAHASHI Yoshiyuki; KANAGAWA Hiroshi
  Japanese journal of veterinary research, 46, 1, 13, 18, 北海道大学, 1998年05月30日, ［査読有り］
  英語, Ovulated mouse oocytes denuded of their cumulus cells, were vitrified in a solution containing 7 M ethylene glycol as the sole cryoprotectant using one or two steps of exposure before vitrification and were diluted in 1 M sucrose solution in 5 or 10 min after warming. The results proved that the viability of oocytes are detrimentally affected by exposure to the vitrification solution even without vitrification. At 5 min dilution time, the two-step exposure was superior to the one-step in terms of the post-warming recovery rate of vitrified oocytes with normal morphology and their subsequent development to the blastocyst stage (p<0.01) after fertilization in vitro. At 10 min dilution time, no significant difference between one- or two-step exposure was found. The effect of the addition of 0.5 M sucrose to the vitrification solution was also determined and did not result in a significant improvement in the viability of oocytes vitrified in one-step and diluted for 10 min. In conclusion, the results in this study indicate that oocytes can be vitrified with 7 M ethylene glycol as the sole cryoprotectant in the vitrification solution, and that the recovery of normal oocytes after one-step exposure in the vitrification solution can be improved by 10 min dilution time. However, the improvement in the recovery rate of oocytes with normal morphology and their subsequent developmental in vitro was not improved by the addition of 0.5 M sucrose to the vitrification solution.
• Functional enucleation of mouse metaphase II oocytes with etoposide
  ELSHEIKH Adil Salim; TAKAHASHI Yoshiyuki; KATAGIRI Seiji; KANAGAWA Hiroshi
  Japanese journal of veterinary research, 45, 4, 217, 220, 北海道大学, 1998年02月27日, ［査読有り］
  英語, Mouse metaphase II (M II) oocytes were exposed to 50 μg/ml etoposide (ETO) before and after parthenogenetic activation with 7% ethanol and they were washed with 0.75 M sucrose. The ETO treated parthenogenetically activated oocytes were cultured or fused to single blastomeres of late 2-cell stage mouse embryo to test their ability to support development in vitro. In parallel untreated parthenogenetically activated oocytes were cultured to serve as control. None of ETO treated oocytes developed beyond the 2-cell stage, whereas 4% of the reconstituted embryos and 35% of control developed to blastocysts. It is concluded that mouse M II oocytes can be functionally enucleated by ETO treatment and can be used for nuclear transfer experiments.

• ウシの低受胎の要因推定に向けた新規検査技術の創出
  内山淳平; 八木沢拓也; 村上裕信; 片桐成二, 食肉に関する助成研究調査成果報告書, 43, 2025年
• 発情後3日目における多血小板血漿の牛子宮内注入が子宮内膜VEGF mRNA発現に及ぼす影響
  梶岡春花; 大崎光仁; 片桐成二; 奥山みなみ; 奥山みなみ; 田村亜久里; 大上來世紀; 大上來世紀; 中田健; 杉浦智親, 日本獣医学会学術集会講演要旨集, 168th, 2025年
• 発情後3日目における多血小板血漿の牛子宮内注入による子宮内膜機能調節への作用
  大崎光仁; 梶岡春花; 片桐成二; 奥山みなみ; 奥山みなみ; 田村亜久里; 大上來世紀; 中田健; 杉浦智親, 日本獣医学会学術集会講演要旨集, 168th, 2025年
• 誘起発情における牛子宮内膜厚調節因子の発現パターンの解明
  大上來世紀; 大上來世紀; 杉浦智親; 中田健; 片桐成二; 奥山みなみ; 桃沢健二; 永野昌志; 奥山みなみ; 桃沢健二; 永野昌志, 日本獣医学会学術集会講演要旨集, 168th, 2025年
• アルパカの生殖行動と血中性ステロイドホルモンの関係
  荒古江美紗; 柳川洋二郎; 西村亮; 山本直樹; 菅野智裕; 片桐成二; 桃沢健二; 永野昌志, 日本野生動物医学会大会・講演要旨集, 30th, 2024年
• ホッキョクグマにおける交尾に合わせた人工授精と排卵誘起
  柳川洋二郎; 鳥居佳子; 鳥居佳子; 永野昌志; 曽地千尋; 田中紘子; 入江陽一; 吉住和規; 橋本渉; 三浦史順; 高橋一斗; 山崎槙; 大崎彩佳; 楠田哲士; 片桐成二, 日本野生動物医学会大会・講演要旨集, 30th, 2024年
• 乳牛における子宮内細菌叢解析の産業利用の可能性
  八木沢拓也; 内山淳平; 片桐成二, 日本細菌学雑誌(Web), 79, 2, 2024年
• 発情期における牛子宮内膜厚調節関連因子と子宮内膜上皮成長因子との関係
  大上來世紀; 片桐成二; 奥山みなみ; 奥山みなみ; 中田健; 杉浦智親, 日本獣医学会学術集会講演要旨集, 167th, 2024年
• 不受胎牛摘発のための乳汁中プロジェステロン濃度測定
  柳川洋二郎; 杉浦智親; 石田晃彦; 渡慶次学; 片桐成二, 日本獣医学会学術集会講演要旨集, 167th, 2024年
• めん羊の発情同期化に用いる腟内プロジェステロン徐放剤処置が人工授精時の腟内細菌叢に与える影響
  齋藤希実; 佐川里子; 白鳥麗奈; 健山幸乃; 鈴木康規; 久保田寛顕; 谷田孝志; 柳川洋二郎; 片桐成二; 菅野智裕; 桃沢健二; 永野昌志, 東北畜産学会報, 74, 2, 2024年
• 初回人工授精前の子宮内膜組織を用いた乳牛の低受胎に関わる子宮内細菌叢の解析
  八木沢 拓也; 内山 淳平; 内山 伊代; 安藤 駿; 市居 修; 村上 裕信; 松下 治; 片桐 成二, 日本細菌学雑誌, 78, 1, 72, 72, 2023年02月
  日本細菌学会, 日本語
• 初回人工授精前の子宮内膜組織を用いた乳牛の低受胎に関わる子宮内細菌叢の解析
  八木沢 拓也; 内山 淳平; 内山 伊代; 安藤 駿; 市居 修; 村上 裕信; 松下 治; 片桐 成二, 日本細菌学雑誌, 78, 1, 72, 72, 2023年02月
  日本細菌学会, 日本語
• 乳牛の分娩前の体温低下,ホルモン動態および分娩経過の関連について
  亀谷牧子; 古川瑛理; 古川瑛理; 池中良徳; 松崎明; 柳川洋二郎; 片桐成二, 日本獣医学会学術集会講演要旨集, 166th, 2023年
• 乳用牛の発情後期および発情休止期における耐糖能の違い
  谷田孝志; 池田侑樹; 田嶋彩野; 田嶋彩野; 菅野智裕; 菅野智裕; 坂口謙一郎; 柳川洋二郎; 永野昌志; 永野昌志; 片桐成二, 日本獣医学会学術集会講演要旨集, 166th, 2023年
• 乳牛における子宮内細菌叢と受胎性との関連についての検討
  八木沢拓也; 内山淳平; 内山伊代; 安藤駿; 市居修; 村上裕信; 松下治; 片桐成二, 北海道獣医師会雑誌, 67, 8, 294, 294, 2023年
  (公社)北海道獣医師会, 日本語
• 生理的な範囲の暑熱負荷が牛初期胞状卵胞由来卵子の発生能および抗酸化能に及ぼす影響
  河野光平; 坂口謙一郎; 坂口謙一郎; CHELENGA Madalitso; NATTAPONG Ninpetch; 小林進太郎; 古川瑛理; 柳川洋二郎; 片桐成二, 日本生殖医学会雑誌, 67, 3, 2022年
• ルーメンセンサから得られる温度データの機械学習による乳牛の分娩予測
  古川瑛理; 檜垣彰吾; 松崎明; 唄花子; 高橋昌志; 片桐成二; 柳川洋二郎, 日本畜産学会大会講演要旨, 130th, 2022年
• 暑熱負荷が牛の初期胞状卵胞に由来する卵子中の活性酸素種および還元型グルタチオン量に及ぼす影響
  河野光平; 坂口謙一郎; 坂口謙一郎; CHELENGA Madalitso; 古川瑛理; NINPETCH Nattapong; 柳川洋二郎; 片桐成二, 日本繁殖生物学会講演要旨集(Web), 114th, 2021年
• 第二胃内留置型自動体温測定器で測定したホルスタイン種経産牛の分娩前1週間の体温変化と分娩時間帯の関係
  古川瑛理; 高橋昌志; 松崎明; 唄花子; 永野昌志; 片桐成二; 柳川洋二郎, 日本畜産学会大会講演要旨, 129th, 2021年
• 乳汁中プロジェステロン濃度測定による発情回帰牛の摘発
  古川瑛理; 安田奈絵; 山田淑子; 石田晃彦; 渡慶次学; 渡邊龍之介; 篠原禎忠; 松田憲司; 野内繁広; 片桐成二; 柳川洋二郎, 日本獣医学会学術集会講演要旨集, 163rd, 2020年
• 暑熱が乳牛の初期胞状卵胞に由来する卵子の発育,成熟および顆粒層細胞の性ステロイドホルモン産生能に及ぼす影響
  河野光平; 坂口謙一郎; 坂口謙一郎; 古川瑛理; CHELENGA Madalitso; 柳川洋二郎; 片桐成二, 日本獣医学会学術集会講演要旨集, 163rd, 2020年
• 精漿が豚の末梢血単核球中のサイトカイン発現および制御性T細胞に与える影響
  阪井紀乃; 奥山みなみ; 奥山みなみ; 對馬隆介; 對馬隆介; 南家夕子; 篠原明; 古川瑛理; 河野光平; 柳川洋二郎; 楢原久司; 片桐成二, 日本獣医学会学術集会講演要旨集, 163rd, 2020年
• 若手研究者の描く獣医繁殖学の未来 クマ科動物の人工授精技術の開発に向けた研究
  鳥居 佳子; 永野 昌志; 片桐 成二; 柳川 洋二郎, 日本獣医学会学術集会講演要旨集, 162回, 269, 269, 2019年08月
  (公社)日本獣医学会, 日本語
• 牛性選別精子の卵管上皮細胞結合能および受精能獲得のフローサイトメトリーによる解析
  中島愛理; 菅野智裕; 菅野智裕; 片桐成二; 永野昌志; 柳川洋二郎, 日本獣医学会学術集会講演要旨集, 162nd, 2019年
• ニホンザルにおけるプロジェステロン作動薬による月経周期同期化
  黒澤拓斗; 黒澤拓斗; 兼子明久; 夏目尊好; 森本真弓; 愛洲星太郎; GRIS Vanessa; TAKESHITA Rafaela Sayuri; 宮部貴子; 岡本宗裕; 永野昌志; 片桐成二; 柳川洋二郎, 日本野生動物医学会大会・講演要旨集, 25th, 2019年
• 液体クロマトグラフィー高分解能質量分析を用いた牛卵子中遊離脂肪酸およびトリアシルグリセロールの分析
  植芝 滉己; 呉 ユエ; 陳 震; 坂口 謙一郎; 柳川 洋二郎; 片桐 成二; 千葉 仁志; 惠 淑萍; 永野 昌志, 日本獣医学会学術集会講演要旨集, 161回, 405, 405, 2018年08月
  (公社)日本獣医学会, 日本語
• LC/Orbitrap-MSを用いた牛卵子中脂質の網羅的解析(Lipidomic profiling in bovine oocytes by LC/Orbitrap-MS)
  呉 げつ; 植芝 滉己; 陳 震; 坂口 謙一郎; 柳川 洋二郎; 片桐 成二; 永野 昌志; 千葉 仁志; 惠 淑萍, JSBMS Letters, 43, Suppl., 105, 105, 2018年08月
  (一社)日本医用マススペクトル学会, 英語
• 乳牛の卵巣内胞状卵胞数が血中卵胞刺激ホルモン動態と卵胞における性ステロイドホルモン産生に与える影響
  坂口謙一郎; 柳川洋二郎; 吉岡耕治; 須田智子; 植芝滉己; 河野光平; 宮本祥代; 片桐成二; 永野昌志, 日本獣医学会学術集会講演要旨集, 161st, 2018年
• 乳牛における暑熱ストレスと子宮内膜中上皮成長因子濃度異常との関係および暑熱の子宮内環境への影響評価のための子宮内温度と子宮内膜血流量の測定法の検討
  河野光平; 柳川洋二郎; NATTAPONG Ninpetch; 坂口謙一郎; 菅野智裕; 菅野智裕; 鳥居佳子; 植芝滉己; 宮本祥代; 永野昌志; 片桐成二, 日本獣医学会学術集会講演要旨集, 161st, 2018年
• クラスター解析の精子受胎性評価への応用:性選別および通常凍結精液中の精子運動性サブポピュレーション構成の比較
  菅野智裕; 菅野智裕; 柳川洋二郎; 片桐成二; 永野昌志, 日本獣医学会学術集会講演要旨集, 161st, 2018年
• ヒグマ精液の凍結保存液に添加する糖の種類および冷却速度が凍結融解後の精液性状に及ぼす影響
  鳥居佳子; 菅野智裕; 蓑原悠太朗; 坂元秀行; 松本直也; 冨安洵平; 松井基純; 永野昌志; 片桐成二; 柳川洋二郎, 日本獣医学会学術集会講演要旨集, 160th, 440, 440, 2017年08月30日
  (公社)日本獣医学会, 日本語
• Astaxanthin improves the growth parameters, developmental competence, and quality of in vitro grown oocytes derived from bovine early antral follicles(和訳中)
  Abdel-Ghani Mohammed.A; 坂口 謙一郎; 菅野 智裕; 柳川 洋二郎; 片桐 成二; 永野 昌志, 日本獣医学会学術集会講演要旨集, 160回, 431, 431, 2017年08月
  (公社)日本獣医学会, 英語
• Mitochondrial activity and reactive oxygen species(ROS) accumulation in bovine oocytes derived from different culture system for in vitro maturation(和訳中)
  Purevdorj Erdenetogtokh; 柳川 洋二郎; 片桐 成二; 永野 昌志, 日本獣医学会学術集会講演要旨集, 160回, 432, 432, 2017年08月
  (公社)日本獣医学会, 英語
• 牛卵巣の大きさが顆粒層細胞の性ステロイドホルモン産生能および卵子核成熟能に与える影響
  坂口 謙一郎; 菅野 智裕; 楊 応華; 柳川 洋二郎; 片桐 成二; 永野 昌志, 北海道獣医師会雑誌, 61, 8, 300, 300, 2017年08月
  (公社)北海道獣医師会, 日本語
• 精子運動能自動解析装置(CASA)を用いた受精能獲得精子の運動性評価
  菅野智裕; 柳川洋二郎; 片桐成二; 永野昌志, 日本獣医学会学術集会講演要旨集, 160th, 2017年
• ニホンザルにおける排卵誘起処置を伴う単回人工授精プログラムの検討
  柳川洋二郎; 菅野智裕; 南晶子; 兼子明久; 印藤頼子; 佐藤容; 木下こづえ; 岡本宗裕; 片桐成二; 永野昌志, 日本獣医学会学術集会講演要旨集, 160th, 2017年
• 内視鏡を用いたヒグマ(Ursus arctos)における子宮内授精の試み
  柳川洋二郎; 鳥居佳子; 菅野智裕; 田嶋彩野; 冨安洵平; 松本直也; 坂元秀行; 亀井利活; 間野勉; 片桐成二; 永野昌志, 日本野生動物医学会大会・講演要旨集, 23rd, 2017年
• 飼育下アフリカゾウ1個体から採取した精液の輸送後および凍結融解後の精子性状
  鳥居佳子; 菅野智裕; 曽地千尋; 宗内一平; 牛尾佳名子; 吉住和規; 千田圭; 橋本渉; 永野昌志; 片桐成二; 柳川洋二郎, 日本野生動物医学会大会・講演要旨集, 23rd, 2017年
• 卵胞刺激ホルモンの尾椎硬膜外腔内単回投与が黒毛和種牛の体内・体外胚生産に及ぼす影響
  坂口 謙一郎; 出田 篤司; 土屋 加那美; 真方 文絵; 小牧 春菜; 佐藤 正明; 酒井 伸一; 馬塲 貴大; 柳川 洋二郎; 永野 昌志; 片桐 成二; 小西 正人, 北海道獣医師会雑誌, 60, 8, 377, 377, 2016年08月
  (公社)北海道獣医師会, 日本語
• 卵胞膜細胞と共培養した牛卵母細胞-顆粒膜細胞複合体の増殖、ステロイド産生とその後の発生能(Growth, steroidogenesis and subsequent developmental competence of bovine oocyte-granulosa cell complex co-cultured with theca cells)
  楊 応華; 菅野 智裕; 坂口 謙一郎; 柳川 洋二郎; 片桐 成二; 永野 昌志, 日本獣医学会学術集会講演要旨集, 159回, 428, 428, 2016年08月
  (公社)日本獣医学会, 英語
• 牛の小型卵母細胞の発生能に対する成熟前培養時間の影響(Effect of prematuration culture duration on developmental competences of bovine small sized oocytes)
  Mohammed.A. Abdle-Gahni; 坂口 謙一郎; 菅野 智裕; 楊 応華; 柳川 洋二郎; 片桐 成二; 永野 昌志, 日本獣医学会学術集会講演要旨集, 159回, 429, 429, 2016年08月
  (公社)日本獣医学会, 英語
• 牛精液の射出順序が精子運動性サブポピュレーション構成に与える影響
  菅野 智裕; 柳川 洋二郎; 片桐 成二; 高橋 芳幸; 永野 昌志, 日本獣医学会学術集会講演要旨集, 159回, 430, 430, 2016年08月
  (公社)日本獣医学会, 日本語
• ペレット法による凍結保存が融解後のニホンザル精液の運動性に与える影響
  柳川 洋二郎; 菅野 智裕; 兼子 明久; 印藤 頼子; 岡本 宗裕; 片桐 成二; 永野 昌志, 日本獣医学会学術集会講演要旨集, 159回, 431, 431, 2016年08月
  (公社)日本獣医学会, 日本語
• 牛の卵子品質と卵巣内卵胞数の関係 体内および体外発育卵子を用いた予備的検討
  永井 克尚; 杉山 ちさと; 楊 応華; 柳川 洋二郎; 片桐 成二; 永野 昌志, The Journal of Reproduction and Development, 61, Suppl., j91, j91, 2015年09月
  日本繁殖生物学会, 日本語
• ニホンザルにおける電気刺激時の電圧が精子採取に与える影響および精子凍結保存法の改善について
  杉本 幸介; 柳川 洋二郎; 菅野 智裕; 高江洲 昇; 兼子 明久; 印藤 頼子; 岡本 宗裕; 片桐 成二; 永野 昌志, 日本獣医学会学術集会講演要旨集, 158回, 381, 381, 2015年08月
  (公社)日本獣医学会, 日本語
• 乳牛の子宮内膜における上皮成長因子濃度の周期的変化と受胎性の関係 (特集 酪農学園大学の教育・研究から)
  片桐 成二, 酪農ジャーナル, 66, 1, 32, 34, 2013年01月
  酪農学園大学エクステンションセンター, 日本語, 速報，短報，研究ノート等（大学，研究機関紀要）
• マウス胞状卵胞由来卵母細胞の成熟培養時の基礎培地と気相中の酸素濃度が減数分裂の進行と発生能に及ぼす影響
  古山 敬祐; 片桐 成二; 高橋 芳幸, The Journal of Reproduction and Development, 54, Suppl., j94, j94, 2008年08月
  (一社)日本繁殖生物学会, 日本語
• マウス卵子の成熟培養時の酸素濃度と培養時間が核成熟動態と発生能に及ぼす影響
  檜垣彰吾; 岸昌生; 永野昌志; 片桐成二; 高橋芳幸, J Reprod Dev, 53, Supplement, J197, 2007年09月25日
  日本語
• 乳用牛における分娩後の卵巣活動および子宮修復と子宮内膜上皮成長因子(EGF)発現の関係
  片桐成二; 奥村嘉子; 永野昌志; 高橋芳幸, 日本獣医学会学術集会講演要旨集, 140th, 152, 2005年08月31日
  日本語
• 乳用牛における卵胞発育ウェーブと子宮内膜上皮成長因子(EGF)発現の関係
  片桐成二; 奥村嘉子; 永野昌志; 高橋芳幸, J Reprod Dev, 51, Supplement, J93, 2005年08月25日
  日本語
• In vitro culture of mouse preantral follicles using membrane inserts and developmental competence of in vitro ovulated oocytes
  AAG Adam; Y Takahashi; S Katagiri; M Nagano, JOURNAL OF REPRODUCTION AND DEVELOPMENT, 50, 5, 579, 586, 2004年10月
  英語
• メンブレンインサートを用いたマウス二次卵胞の体外培養と培養卵胞から排卵された卵子の発生能
  高橋 芳幸; 片桐 成二; Adam A.A.G.; ほか1名, The Journal of reproduction and development, 50, 5, 579, 586, 2004年10月
  マウスの二次卵胞（直径150-200μm）を卵巣から機械的に単離してメンブレンインサートあるいは微小滴中で個別に5-6日間培養したのち、培地（αMEM）にhCGを添加して排卵を誘起した。その結果、メンブレンインサートおよび微小滴中で培養した卵胞の生存率（83 vs. 77％）に有意差は認められなかった。しかし、メンブレンインサート中で培養した卵胞の方が排卵率は高かった（63 vs. 39％、P, Japanese Society of Animal Reproduction, 日本語
• Rapid sexing of bovine preimplantation embryos using loop-mediated isothermal amplification
  H Hirayama; S Kageyama; S Moriyasu; K Sawai; S Onoe; Y Takahashi; S Katagiri; K Toen; K Watanabe; T Notomi; H Yamashina; S Matsuzaki; A Minamihashi, THERIOGENOLOGY, 62, 5, 887, 896, 2004年09月
  英語
• CIDR処理に併用する高用量エストロジェン製剤が乳用牛の卵胞発育動態に及ぼす影響
  奥村嘉子; 片桐成二; 永野昌志; 高橋芳幸, J Reprod Dev, 50, Supplement, J81, 2004年08月25日
  日本語
• Effects of oxygen tension in the gas atmosphere during in vitro maturation, in vitro fertilization and in vitro culture on the efficiency of in vitro production of mouse embryos
  AAG Adam; Y Takahashi; S Katagiri; M Nagano, JAPANESE JOURNAL OF VETERINARY RESEARCH, 52, 2, 77, 84, 2004年08月
  英語
• 血尿を主訴とした雌ウサギの子宮疾患例
  永野昌志; 片桐成二; 滝口満喜; 小松智彦; 永島太郎; 井川真一; 高橋芳幸, 北海道獣医師会雑誌, 48, 8, 318, 318, 2004年08月01日
  (公社)北海道獣医師会, 日本語
• 犬の真性半陰陽の1例
  藤木亮介; 永野昌志; 小西郁男; 穴川明子; 奥村嘉子; 斉藤千寛; 片桐成二; 高橋芳幸, 北海道獣医師会雑誌, 48, 8, 318, 2004年08月01日
  日本語
• Changes in EGF concentrations during estrous cycle in bovine endometrium and their alterations in repeat breeder cows
  S Katagiri; Y Takahashi, THERIOGENOLOGY, 62, 1-2, 103, 112, 2004年07月, ［国際誌］
  英語
• Follicular development after ovum pick-up and fertilizability of retrieved oocytes in postpartum dairy cattle
  Y Sasamoto; M Sakaguchi; M Nagano; S Katagiri; Y Takahashi, JAPANESE JOURNAL OF VETERINARY RESEARCH, 51, 3-4, 151, 159, 2004年02月
  英語
• 母体の妊娠認識メカニズムと影響する要因
  酪農ジャーナル 臨時増刊号, 2004年
• Vitrification of bovine oocytes and its application to intergeneric somatic cell nucleus transfer
  EC Atabay; Y Takahashi; S Katagiri; M Nagano; A Koga; Y Kanai, THERIOGENOLOGY, 61, 1, 15, 23, 2004年01月
  英語
• Relationship between endometrial concentrations of epidermal growth factor (EGF) and preimplantation embryo development in dairy cattle.
  S Katagiri; Y Takahashi, BIOLOGY OF REPRODUCTION, 211, 211, 2004年
  英語, 研究発表ペーパー・要旨（国際会議）
• The effects of twisting and type of aspiration needle on the efficiency of transvaginal ultrasound-guided ovum pick-up in cattle
  Y Sasamoto; M Sakaguchi; S Katagiri; Y Yamada; Y Takahashi, JOURNAL OF VETERINARY MEDICAL SCIENCE, 65, 10, 1083, 1086, 2003年10月
  英語
• Effect of fusion･activation protocol on in vitro development of porcine nuclear transfer embryos constructed with foreign gene-transfected fetal fibroblast
  MAM Diaz; T Mori; M Nagano; S Katagiri; Y Takahashi, J Vet Med Sci, 65, 9, 989, 994, 2003年09月
  英語
• 分娩後のウシ子宮内膜上皮におけるPAGファミリーの遺伝子発現について
  橋爪 一善; 石渡 広子; 坂口 実; 片桐 成二; 木崎 景一郎; 今井 敬; 高橋 透; 平澤 明; 塩島 聡; 勝間 進; 辻本 豪三, 日本畜産学会大会講演要旨集, 101回, 86, 86, 2003年03月
  (公社)日本畜産学会, 日本語
• Effect of activation treatments of recipient oocytes on subsequent development of bovine nuclear transfer embryos
  EC Atabay; S Katagiri; M Nagano; Y Takahashi, JAPANESE JOURNAL OF VETERINARY RESEARCH, 50, 4, 185, 194, 2003年02月
  英語
• Changes in sexual behavior and fecal steroid hormone concentrations during the breeding season in female Hokkaido brown bears (Ursus arctos yesoensis) under captive condition
  A Ishikawa; H Sakamoto; S Katagiri; Y Takahashi, JOURNAL OF VETERINARY MEDICAL SCIENCE, 65, 1, 99, 102, 2003年01月
  英語
• 連続ちつ温測定による乳牛の分娩時刻予知
  関塚次郎; 高橋芳幸; 片桐成二; 永野昌志; 坂口実; 山田豊; 中辻浩喜, 北海道獣医師会雑誌, 46, 8, 239, 2002年08月01日
  日本語
• Efficiency of fecal steroid hormone measurement for assessing reproductive function in the Hokkaido brown bear (Ursus arctos yesoensis)
  A Ishikawa; S Kikuchi; S Katagiri; H Sakamoto; Y Takahashi, JAPANESE JOURNAL OF VETERINARY RESEARCH, 50, 1, 17, 27, 2002年05月
  英語
• Cryopreservation of the semen collected by electroejaculation from the Hokkaido brown bear (Ursus arctos yesoensis)
  A Ishikawa; M Matsui; H Sakamoto; S Katagiri; Y Takahashi, JOURNAL OF VETERINARY MEDICAL SCIENCE, 64, 4, 373, 376, 2002年04月
  英語
• Birth of pups after transfer of mouse embryos derived from vitrified preantral follicles
  EC dela Pena; Y Takahashi; S Katagiri; EC Atabay; M Nagano, REPRODUCTION, 123, 4, 593, 600, 2002年04月
  英語
• 獣医繁殖学マニュアル
  文永堂出版, 59-61, 2002年
• Thatcher WW, Moreira F, Santos J, Mattos R. Novel new concepts for reproductive management and strategies to improve reproductive efficiency in dary cattle（乳牛の新しい繁殖管理法と繁殖効率改善の戦略、訳 片桐成二）
  日本獣医師会雑誌, 55:203-207, 2002年
• Soliman M, Ishioka K, Yoshida R, Komabayashi K, Hatai H, Matsui Y, Hirai T, Katagiri S, Takahashi Y, Kawakita Y, Abe H, Kitamura H, Kimura K, Saito M. Serum leptin levels during the periparturient period in cows.
  J Vet Med Sci, 64:1053-1056, 2002年
• Kobayashi A, Katagiri S, Kimura T, Ochiai K, Umemura T. Steroid hormones do not reactivate Neospora caninum in ovariectomized mice.
  J Vet Med Sci, 64:773-777, 2002年
• Soliman M, Ishioka K, Yoshida R, Komabayashi K, Hatai H, Matsui Y, Hirai T, Katagiri S, Takahashi Y, Kawakita Y, Abe H, Kitamura H, Kimura K, Saito M. Serum leptin levels during the periparturient period in cows.
  J Vet Med Sci, 64:1053-1056, 2002年
• Kobayashi A, Katagiri S, Kimura T, Ochiai K, Umemura T. Steroid hormones do not reactivate Neospora caninum in ovariectomized mice.
  J Vet Med Sci, 64:773-777, 2002年
• 乳牛における分娩後の卵胞発育と卵胞内卵子の受精能
  笹本良彦; 坂口実; 山田豊; 永野昌志; 片桐成二; 高橋芳幸, 日本獣医学会学術集会講演要旨集, 132nd, 228, 2001年09月07日
  日本語
• マウスの卵子,はいおよび胎子臓器における脱共役タンパクの発現
  古畑ちひろ; 片桐成二; 高橋芳幸; 永野昌志; 木村和弘; 斉藤昌之, 日本不妊学会雑誌, 46, 3, 183, 2001年07月01日
  日本語
• ウシ子宮膜におけるプロスタグランジン(PG)産生における上皮成長因子(EGF)の役割 単離培養細胞および組織片を用いた検討
  福井秀樹; 片桐成二; 高橋芳幸; 永野昌志, 日本不妊学会雑誌, 46, 3, 182-183, 2001年07月01日
  日本語
• In vitro growth of mouse ovarian preantral follicles and the capacity of their oocytes to develop to the blastocyst stage
  C Bishonga; Y Takahashi; S Katagiri; M Nagano; A Ishikawa, JOURNAL OF VETERINARY MEDICAL SCIENCE, 63, 6, 619, 624, 2001年06月
  英語
• Vitrification of mouse oocytes in ethylene glycol-raffinose solution: Effects of preexposure to ethylene glycol or raffinose on oocyte viability
  EC dela Pena; Y Takahashi; EC Atabay; S Katagiri; M Nagano, CRYOBIOLOGY, 42, 2, 103, 111, 2001年03月
  英語
• Relationship among growth, steroid production and immunolocalization of transforming growth factor-beta 1 in the normally developing mouse follicles cultured in vitro
  C Bishonga; Y Takahashi; S Katagiri; M Nagano; A Ishikawa, JAPANESE JOURNAL OF VETERINARY RESEARCH, 48, 4, 169, 176, 2001年02月
  英語
• Heath SE. 災害発生に伴う動物の救護について (訳 片桐成二)
  北海道獣医師会雑誌, 45:15-18, 2001年
• Wolfgang Jochle. End user attitude toward animal welfare and the environmental issues involved（動物福祉とそれに関連する環境問題に対する消費者の姿勢、訳 片桐成二)
  臨床獣医, 19:43-47, 2001年
• 片桐成二. 卵子形成と成熟、獣医繁殖学 第2版（森純一、金川弘司、浜名克己 編）
  永堂出版, 45-56, 2001年
• 片桐成二. 暑熱ストレス環境下における繁殖成績向上のためのマネージメント
  臨床獣医, 19: 30-34, 2001年
• Bishonga C, Takahashi Y, Katagiri S, Nagano M. Immunolocalization of transforming growth factor-β1 in the ovarian follicular compartments of the adult mouse at diestrus, proestrus and after treatment with human chorionic gonadotropin.
  Christopher Bishonga; Yoshiyuki Takahashi; Seiji Katagiri; Masashi Nagano, J Reprod Dev, 47, 2, 91, 96, 2001年
  The Japanese Society of Animal Reproduction (JSAR), 英語
• Bishonga C, Takahashi Y, Katagiri S, Nagano M, Ishikawa A. Relationship among growth, steroid production and immunolocalization of transforming growth factor-β1 in the normally developing mouse follicles cultured in vitro.
  Jpn J Vet Res, 48: 169-176, 2001年
• Immunolocalization of transforming growth factor-β1 in the ovarian follicular compartments of the adult mouse at diestrus, proestrus and after treatment with human chorionic gonadotropin
  Christopher Bishonga; Yoshiyuki Takahashi; Seiji Katagiri; Masashi Nagano, Journal of Reproduction and Development, 47, 2, 91, 96, 2001年
  The Japanese Society of Animal Reproduction (JSAR), 英語
• ウシの体細胞核移植におけるドナー細胞とレシピエント卵子の細胞周期が再構築はいの発生および初期化に及ぼす影響
  高橋芳幸; 片桐成二; 永野昌志; NOUR M S M, 食肉に関する助成研究調査成果報告書, 18, 11-15, 2000年12月
  日本語
• ウシの体外受精 廃用決定された優良雌牛からのはい生産例
  永野昌志; 高橋芳幸; 片桐成二; 竹下章; 森好政晴; 横田修, 北海道獣医師会雑誌, 44, 7, 196, 2000年07月01日
  日本語
• ウシ子宮内膜間質細胞にとけるプロスタグランジンの合成制御 プロジェストロン,エストロジェンおよび上皮成長因子の役割
  山下傑夫; 片桐成二; 永野昌志; 高橋芳幸, 日本不妊学会雑誌, 45, 2, 165, 2000年04月01日
  日本語
• ウシ一次卵胞の発育能の検討
  山本直人; 永野昌志; 片桐成二; 高橋芳幸, 日本不妊学会雑誌, 45, 2, 165, 2000年04月01日
  日本語
• 初期胞状卵胞由来ウシ卵母細胞の体外発育および成熟
  猪川真紀; 永野昌志; 片桐成二; 高橋芳幸, 日本不妊学会雑誌, 45, 2, 165, 2000年04月01日
  日本語
• Cheong HT, Ikeda K, Martinez Diaz MA., Katagiri S and Takahashi Y. Development of reconstituted pig embryos by nuclear transfer of cultured cumulus cells.
  Reprod Fertil Dev, 12: 15-20, 2000年
• dela Pena EC、Atabay EC、永野昌志、片桐成二、高橋芳幸. エチレングリコールとラフィノースを用いたマウス卵子のガラス化保存における前処理の効果
  北海道牛受精卵移植研究会会報, 19: 31-34, 2000年
• 永野昌志、猪川真紀、山本直人、片桐成二、高橋芳幸. ウシの初期胞状卵胞および一次卵胞の体外培養
  北海道牛受精卵移植研究会会報, 19: 8-13, 2000年
• Cheong HT, Ikeda K, Martinez Diaz MA., Katagiri S and Takahashi Y. Development of reconstituted pig embryos by nuclear transfer of cultured cumulus cells.
  Reprod Fertil Dev, 12: 15-20, 2000年
• Effect of medium change on the development of in vitro matured and fertilized bovine oocytes cultured in medium containing amino acids
  K Ikeda; Y Takahashi; S Katagiri, JOURNAL OF VETERINARY MEDICAL SCIENCE, 62, 1, 121, 123, 2000年01月
  英語
• In vitro fertilization and cortical granule distribution of bovine oocytes having heterogeneous ooplasm with dark clusters
  M Nagano; Y Takahashi; S Katagiri, JOURNAL OF VETERINARY MEDICAL SCIENCE, 61, 5, 531, 535, 1999年05月
  英語
• 笹本良彦、片桐成二、高橋芳幸. ウシの超音波誘導経腟採卵において卵胞吸引時の吸引針の回転と吸引針の違いが卵子回収成績に及ぼす影響
  北海道牛受精卵移植研究会会報, 18: 19-22, 1999年
• The efficacy of the water purification system with an ultra violet lamp and ultrafilter for the preparation of bovine embryo culture media
  Masashi Nagano; Yoshiyuki Takahashi; Seiji Katagiri, Journal of Reproduction and Development, 45, 3, 239, 242, 1999年
  The Japanese Society of Animal Reproduction (JSAR), 英語
• A delayed-implantation-associated protein prevents resumption of DNA synthesis by the trophectoderm of delayed-implanting mouse blastocysts in vitro
  S Katagiri; Y Takahashi; H Kanagawa; BH Yuen; YS Moon, JOURNAL OF VETERINARY MEDICAL SCIENCE, 60, 7, 791, 794, 1998年07月
  英語
• 永野昌志、高橋芳幸、片桐成二、金川弘司. ウシの胞状卵胞から回収した未成熟卵子の超微形態
  北海道牛受精卵移植研究会会報, 17: 1-6, 1998年
• Bautista JAN, Dela Pena EC, Katagiri S, Takahashi Y, Kanagawa H. In vitro viability of mouse oocytes vitrified in an ethylene glycol-based solution.
  Jpn J Vet Res, 46: 13-18, 1998年
• Elsheikh AS, Takahashi Y, Katagiri S, Kanagawa H. Functional enucleation of mouse metaphase II oocytes with etoposide.
  Jpn J Vet Res, 45: 217-220, 1998年
• Bautista JAN, Dela Pena EC, Katagiri S, Takahashi Y, Kanagawa H. In vitro viability of mouse oocytes vitrified in an ethylene glycol-based solution.
  Jpn J Vet Res, 46: 13-18, 1998年
• Elsheikh AS, Takahashi Y, Katagiri S, Kanagawa H. Functional enucleation of mouse metaphase II oocytes with etoposide.
  Jpn J Vet Res, 45: 217-220, 1998年
• Insulin-like growth factor-1 improves development of 8-cell rat embryos in vitro and subsequent development in vivo
  Seiji Katagiri; Basil H.O. Yuen; Young S. Moon, Journal of Reproduction and Development, 44, 1, 15, 20, 1998年
  The Japanese Society of Animal Reproduction (JSAR), 英語
• A somatostatin analogue decreases embryonic loss following superovulation in rats by normalizing insulin-like growth factor-I action in the uterus
  S Katagiri; YS Moon; BH Yuen, HUMAN REPRODUCTION, 12, 4, 671, 676, 1997年04月
  英語
• Mohamed Mohamed Nour、高橋芳幸、片桐成二、金川弘司. ウシ核移植胚の発育に及ぼすレシピエント卵子の品質の影響
  北海道牛受精卵移植研究会会報, 16: 40-43, 1997年
• Role for insulin-like growth factor I in the regulation of electrolyte composition of uterine luminal fluid
  S Katagiri; S Ma; BH Yuen; YS Moon, JOURNAL OF REPRODUCTION AND FERTILITY, 109, 1, 115, 120, 1997年01月
  英語
• An improved technique for molecular cytogenetic analysis of human preimplantation embryos with fluorescence in situ hybridization
  S Ma; DK Kalousek; BH Yuen; S Katagiri; YS Moon, JOURNAL OF REPRODUCTIVE MEDICINE, 41, 6, 379, 383, 1996年06月
  英語
• The role for the uterine insulin-like growth factor I in early embryonic loss after superovulation in the rat
  S Katagiri; YS Moon; BH Yuen, FERTILITY AND STERILITY, 65, 2, 426, 436, 1996年02月
  英語
• SEPARATION OF A 170-K DELAYED-IMPLANTATION-ASSOCIATED PROTEIN WITH INHIBITORY ACTIVITY ON TROPHOBLAST OUTGROWTH AND RNA-SYNTHESIS BY MOUSE EMBRYO
  S KATAGIRI; BH YUEN; YS MOON; Y TAKAHASHI; H KANAGAWA, AMERICAN JOURNAL OF REPRODUCTIVE IMMUNOLOGY, 31, 2-3, 141, 150, 1994年03月
  英語
• Ma S, Kalousek DK, Ho Yuen B, Gomel V, Katagiri S, Moon YS. Chromosome investigation in in vitro fertilization failure.
  J Assis Reprod Genetics, 11: 445-451, 1994年
• Ma S, Kalousek DK, Ho Yuen B, Gomel V, Katagiri S, Moon YS. Chromosome investigation in in vitro fertilization failure.
  J Assis Reprod Genetics, 11: 445-451, 1994年
• PMSG PROFILES IN SUPEROVULATED AND ANTI-PMSG ANTISERUM TREATED MICE AND HEIFERS WITH ENZYME-IMMUNOASSAY
  S KATAGIRI; Y TAKAHASHI; M HISHINUMA; H KANAGAWA; O DOCHI; H TAKAKURA, JAPANESE JOURNAL OF VETERINARY RESEARCH, 39, 1, 11, 21, 1991年05月
  英語
• 片桐成二、首藤文栄、高橋芳幸、金川弘司. ボツリヌス菌産生C1型（C-ST）毒素および酵素（C3）が胚の発育に及ぼす影響
  北海道牛受精卵移植研究会会報, 10: 81-84, 1991年
• 浦野浩司、片桐成二、菱沼 貢、高橋芳幸、金川弘司. ウシ胚回収用フィルターの検討
  浦野 浩司; 片桐 成二; 菱沼 貢; 高橋 芳幸; 金川 弘司, Jpn J Anim Reprod, 33: 48-50, 1, 48, 50, 1987年
  2種類の牛胚回収用フィルターの有用性について検討を加えた。供試卵を一定量の灌流液とともにフィルターを用いてろ過した結果,いずれのフィルターでも98.3%の供試卵を回収することができた。しかし,少数(7.6%)ではあるがフィルターを洗浄した液からも供試卵が回収され,フィルター内を洗浄する必要のあることが示唆された。, THE SOCIETY FOR REPRODUCTION AND DEVELOPMENT, 日本語
• 菱沼 貢、片桐成二、橘田達慶、西山栄治、高橋芳幸、金川弘司. 犬および猫子宮蓄膿症の発症傾向、臨床症状と血液検査所見について
  北海道獣医師会雑誌, 29: 272-276, 1985年

• リピートブリーダー牛におけるオステオポンチン処置前後の子宮内膜上皮成長因子濃度の 変化と受胎率の関係
  藤川 健; 谷田孝志; 河野光平; 栁川洋二郎; 片桐成二
  第42回日本獣医師会獣医学術学会年次大会
  2025年01月24日 - 2025年01月26日
• Effects of combined treatment of OPN peptide and hormones on endometrial epidermal growth factor (EGF) concentration and fertility in postpartum dairy cows
  Bello T.K, Tanida T, Tagami T, Yanagawa Y, Katagiri S.
  The 117th Annual Meeting of the Society for Reproduction and Development
  2024年09月22日 - 2024年09月25日
• オステオポンチンのインテグリン結合モチーフを含むペプチドの腟内投与が乳牛の子宮、腟および末梢血単核球の炎症性反応に及ぼす効果
  谷田孝志; 杉浦智親; 大上來世紀; 森本えみり; 山村瑞穂; 清水純奈; 田村亜久里; 坂口謙一郎; 栁川洋二郎; 片桐成二
  第117回日本繁殖生物学会大会, 2024年09月23日
• 牛子宮内膜における上皮成長因子発現に対するToll様受容体4を介した熱ショックタンパク質の効果
  斎藤萌佳; 坂口謙一郎; 谷田孝志; 栁川洋二郎; 片桐成二
  第167回日本獣医学会学術集会, 2024年09月12日
• 牛の受胎性向上効果を持つオステオポンチンのインテグリン結合モチーフを含むペプチドが培養下の牛末梢血単核球の炎症性サイトカイン遺伝子発現に及ぼす効果
  谷田孝志; 坂口謙一郎; 栁川洋二郎; 片桐成二
  第167回日本獣医学会学術集会, 2024年09月12日
• 発情期における牛子宮内膜厚調節関連因子と子宮内膜上皮成長因子との関係
  大上來世紀; 片桐成二; 奥山みなみ; 中田健; 杉浦智親
  第167回日本獣医学会学術集会, 2024年09月12日
• 乳牛の血漿遊離脂肪酸濃度上昇に伴う卵子エネルギー代謝関連脂質プロファイルの変化
  古川瑛理; 陳震; 窪友瑛; CHELENGA Madalitso; WU Yue; 千葉仁志; 柳川洋二郎; 片桐成二; 惠淑萍; 永野昌志
  日本生殖医学会雑誌, 2022年
  2022年 - 2022年
• 第二胃内留置型自動体温測定器で測定したホルスタイン種経産牛の分娩前1週間の体温変化と分娩時間帯の関係
  古川 瑛理; 高橋 昌志; 松崎 明; 唄 花子; 永野 昌志; 片桐 成二; 柳川 洋二郎
  日本畜産学会大会講演要旨集, 2021年09月, (公社)日本畜産学会, 日本語
  2021年09月 - 2021年09月
• 乳牛における子宮内膜上皮増殖因子(EGF)回復およびその後の受胎率の変化に対する危険因子【JST・京大機械翻訳】
  NATTAPONG Ninpetch; 河野光平; 柳川洋二郎; 片桐成二
  日本獣医学会学術集会講演要旨集, 2021年
  2021年 - 2021年
• ホルスタイン種泌乳牛の分娩後日数及びボディコンディションスコアと卵子中トリアシルグリセロール量の関係
  古川瑛理; 陳震; 窪友瑛; MADALITSO Chelenga; YUE Wu; 千葉仁志; 柳川洋二郎; 片桐成二; 惠淑萍; 永野昌志
  日本獣医学会学術集会講演要旨集, 2021年
  2021年 - 2021年
• 液体クロマトグラフィー質量分析法によるアフリカゾウの血中ステロイドホルモン濃度測定法の確立および無排卵雌における排卵誘起の試み
  篠原明; 篠原明; 鳥居佳子; 入江陽一; 牛尾佳名子; 曽地千尋; 宗内一平; 楠田哲士; 東達也; 一瀬貴大; 中山翔太; 石塚真由美; 池中良徳; 片桐成二; 柳川洋二郎
  日本獣医学会学術集会講演要旨集, 2021年
  2021年 - 2021年
• リピートブリーダー牛にて、子宮内膜の上皮成長因子profileinを正常化する乳由来オステオポンチンの効果(Capacity of milk osteopontin to normalize endometrial epidermal growth factor profilein repeat breeder cows)
  Kyaw Hay Mar; 田上 貴祥; 柳川 洋二郎; 永野 昌志; 片桐 成二
  日本獣医学会学術集会講演要旨集, 2020年10月, (公社)日本獣医学会, 英語
  2020年10月 - 2020年10月
• 卵巣内の主席卵胞と黄体の存在が初期胞状卵胞由来卵子の核成熟能と顆粒層細胞の性ステロイドホルモン産生能に及ぼす影響
  坂口 謙一郎; 河野 光平; 柳川 洋二郎; 片桐 成二; 永野 昌志
  日本獣医学会学術集会講演要旨集, 2020年10月, (公社)日本獣医学会, 日本語
  2020年10月 - 2020年10月
• 非泌乳期ホルスタイン種経産雌牛における卵胞刺激ホルモンの尾椎硬膜外腔投与後の血漿中性ステロイドホルモン動態
  坂口 謙一郎; 柳川 洋二郎; Ninpetch Nattapong; 河野 光平; 須田 智子; 吉岡 耕治; 片桐 成二; 永野 昌志
  The Journal of Reproduction and Development, 2020年09月, (公社)日本繁殖生物学会, 日本語
  2020年09月 - 2020年09月
• 組換えオステオポンチンによるリピートブリーダー牛の子宮内膜上皮成長因子(EGF)濃度正常化と受胎性回復効果の検証
  佐藤 弘子; Hay Mar Kyaw; 柳川 洋二郎; 永野 昌志; 田上 貴祥; 片桐 成二
  Journal of Mammalian Ova Research, 2020年07月, (一社)日本卵子学会, 日本語
  2020年07月 - 2020年07月
• 組み換えオステオポンチンによる牛子宮内膜上皮成長因子濃度の正常化効果の検証
  佐藤弘子; KYAW Hay Mar; 柳川洋二郎; 永野昌志; 田上貴祥; 片桐成二
  Journal of Reproduction and Development, 2019年09月05日, 日本語
  2019年09月05日 - 2019年09月05日
• 牛性選別精子の卵管上皮細胞結合能および受精能獲得のフローサイトメトリーによる解析
  中島愛理; 菅野智裕; 菅野智裕; 片桐成二; 永野昌志; 柳川洋二郎
  日本獣医学会学術集会講演要旨集, 2019年08月20日, 日本語
  2019年08月20日 - 2019年08月20日
• クマ科動物の人工授精技術の開発に向けた研究
  鳥居佳子; 永野昌志; 片桐成二; 柳川洋二郎
  日本獣医学会学術集会講演要旨集, 2019年08月20日, 日本語
  2019年08月20日 - 2019年08月20日
• 乳牛の子宮内膜組織血流量に影響を及ぼす因子の解析
  河野光平; 柳川洋二郎; NATTAPONG Ninpetch; 永野昌志; 片桐成二
  日本獣医学会学術集会講演要旨集, 2019年08月20日, 日本語
  2019年08月20日 - 2019年08月20日
• Identification of seminal plasma proteins to normalize endometrial epidermal growth factor concentrations in repeat breeder cows
  BADRAKH Dagvajamts; 柳川洋二郎; 永野昌志; 片桐成二
  日本獣医学会学術集会講演要旨集, 2019年08月20日, 英語
  2019年08月20日 - 2019年08月20日
• 精漿蛋白による子宮機能調節とその低受胎対策への応用
  片桐成二
  Journal of Reproduction and Development, 2019年
  2019年 - 2019年
• モンゴル国における羊体外受精卵由来産子作出の試み：体外成熟培地への抗酸化剤アスタキサンチンの添加効果
  永野昌志; Purevdorj Erdenetogtokh; 栁川洋二郎; 片桐成二
  北海道牛受精卵移植研究会会報, 2018年09月, 日本語
  2018年09月 - 2018年09月
• Lipidomic profiling in bovine oocytes by LC/Orbitrap-MS
  WU Yue; UESHIBA Hiroki; CHEN Zhen; SAKAGUCHI Kenichiro; YANAGAWA Yojiro; KATAGIRI Seiji; NAGANO Masashi; CHIBA Hitoshi; CHIBA Hitoshi; HUI Shu‐Ping
  JSBMS Letters, 2018年08月25日, 英語
  2018年08月25日 - 2018年08月25日
• 液体クロマトグラフィー高分解能質量分析を用いた牛卵子中遊離脂肪酸およびトリアシルグリセロールの分析
  植芝滉己; 呉ユエ, 陳震; 坂口謙一郎; 柳川洋二郎; 片桐成二; 千葉仁志; 千葉仁志; 惠淑萍; 永野昌志
  日本獣医学会学術集会講演要旨集, 2018年08月21日, 日本語
  2018年08月21日 - 2018年08月21日
• 乳牛の卵巣内胞状卵胞数が血中卵胞刺激ホルモン動態と卵胞における性ステロイドホルモン産生に与える影響
  坂口謙一郎; 柳川洋二郎; 吉岡耕治; 須田智子; 植芝滉己; 河野光平; 宮本祥代; 片桐成二; 永野昌志
  日本獣医学会学術集会講演要旨集, 2018年08月21日, 日本語
  2018年08月21日 - 2018年08月21日
• クラスター解析の精子受胎性評価への応用:性選別および通常凍結精液中の精子運動性サブポピュレーション構成の比較
  菅野智裕; 菅野智裕; 柳川洋二郎; 片桐成二; 永野昌志
  日本獣医学会学術集会講演要旨集, 2018年08月21日, 日本語
  2018年08月21日 - 2018年08月21日
• 乳牛における暑熱ストレスと子宮内膜中上皮成長因子濃度異常との関係および暑熱の子宮内環境への影響評価のための子宮内温度と子宮内膜血流量の測定法の検討
  河野光平; 柳川洋二郎; NATTAPONG Ninpetch; 坂口謙一郎; 菅野智裕; 菅野智裕; 鳥居佳子; 植芝滉己; 宮本祥代; 永野昌志; 片桐成二
  日本獣医学会学術集会講演要旨集, 2018年08月21日, 日本語
  2018年08月21日 - 2018年08月21日
• 卵胞刺激ホルモンおよび性腺刺激ホルモン放出ホルモン投与による卵巣刺激が河川型水牛 (Bubalus bubalis) における経腟採卵-体外受精成績に及ぼす影響
  坂口謙一郎; Excel Rio S. Maylem; Ramesh C. Tilwani; 栁川洋二郎; 片桐成二; Edwin C. Atabay; Eufrocina P. Atabay; 永野昌志
  北海道牛受精卵移植研究会会報, 2018年08月, 日本語
  2018年08月 - 2018年08月
• ペレット法により凍結したニホンザル精液に対する融解法の違いが精子性状に与える影響
  栁川洋二郎; 菅野智裕; 兼子明久; 印藤頼子; 佐藤容; 木下こづえ; 今井啓雄; 平井啓久; 片桐成二; 永野昌志; 岡本宗裕
  Cryopreservation conference 2017, 2017年11月, 日本語
  2017年11月 - 2017年11月
• ニホンザルにおける排卵誘起処置を伴う単回人工授精プログラムの検討
  柳川洋二郎; 菅野智裕; 南晶子; 兼子明久; 印藤頼子; 佐藤容; 木下こづえ; 岡本宗裕; 片桐成二; 永野昌志
  日本獣医学会学術集会講演要旨集, 2017年08月30日, 日本語
  2017年08月30日 - 2017年08月30日
• 牛卵巣内胞状卵胞数と初期胞状卵胞由来卵子‐顆粒層細胞複合体の顆粒層細胞増殖能および卵子発生能の関連性
  坂口謙一郎; 谷田孝志; 谷田孝志; 楊応華; 菅野智裕; 永井克尚; 永井克尚; MOHAMED. A. Abdel‐Ghani; 柳川洋二郎; 片桐成二; 永野昌志
  日本獣医学会学術集会講演要旨集, 2017年08月30日, 日本語
  2017年08月30日 - 2017年08月30日
• ヒグマ精液の凍結保存液に添加する糖の種類および冷却速度が凍結融解後の精液性状に及ぼす影響
  鳥居佳子; 菅野智裕; 蓑原悠太朗; 坂元秀行; 松本直也; 冨安洵平; 松井基純; 永野昌志; 片桐成二; 柳川洋二郎
  日本獣医学会学術集会講演要旨集, 2017年08月30日, 日本語
  2017年08月30日 - 2017年08月30日
• 精子運動能自動解析装置(CASA)を用いた受精能獲得精子の運動性評価
  菅野智裕; 柳川洋二郎; 片桐成二; 永野昌志
  日本獣医学会学術集会講演要旨集, 2017年08月30日, 日本語
  2017年08月30日 - 2017年08月30日
• 黒毛和種リピートブリーダー牛の子宮内膜上皮成長因子発現異常に対する治療への抵抗性と肥満との関係
  谷田孝志; 谷田孝志; 坂口謙一郎; 菅野智裕; 池田侑樹; 田嶋彩野; 柳川洋二郎; 永野昌志; 片桐成二
  日本獣医学会学術集会講演要旨集, 2017年08月30日, 日本語
  2017年08月30日 - 2017年08月30日
• 牛卵巣の大きさが顆粒層細胞の性ステロイドホルモン産生能および卵子核成熟能に与える影響
  坂口 謙一郎; 菅野 智裕; 楊 応華; 柳川 洋二郎; 片桐 成二; 永野 昌志
  北海道獣医師会雑誌, 2017年08月, (公社)北海道獣医師会, 日本語
  2017年08月 - 2017年08月
• Mitochondrial activity and reactive oxygen species(ROS) accumulation in bovine oocytes derived from different culture system for in vitro maturation(和訳中)
  Purevdorj Erdenetogtokh; 柳川 洋二郎; 片桐 成二; 永野 昌志
  日本獣医学会学術集会講演要旨集, 2017年08月, (公社)日本獣医学会, 英語
  2017年08月 - 2017年08月
• Astaxanthin improves the growth parameters, developmental competence, and quality of in vitro grown oocytes derived from bovine early antral follicles(和訳中)
  Abdel-Ghani Mohammed.A; 坂口 謙一郎; 菅野 智裕; 柳川 洋二郎; 片桐 成二; 永野 昌志
  日本獣医学会学術集会講演要旨集, 2017年08月, (公社)日本獣医学会, 英語
  2017年08月 - 2017年08月
• ペレット法による凍結保存が融解後のニホンザル精液の運動性に与える影響
  柳川 洋二郎; 菅野 智裕; 兼子 明久; 印藤 頼子; 岡本 宗裕; 片桐 成二; 永野 昌志
  日本獣医学会学術集会講演要旨集, 2016年08月, (公社)日本獣医学会, 日本語
  2016年08月 - 2016年08月
• 牛精液の射出順序が精子運動性サブポピュレーション構成に与える影響
  菅野 智裕; 柳川 洋二郎; 片桐 成二; 高橋 芳幸; 永野 昌志
  日本獣医学会学術集会講演要旨集, 2016年08月, (公社)日本獣医学会, 日本語
  2016年08月 - 2016年08月
• 牛の小型卵母細胞の発生能に対する成熟前培養時間の影響(Effect of prematuration culture duration on developmental competences of bovine small sized oocytes)
  Mohammed.A. Abdle-Gahni; 坂口 謙一郎; 菅野 智裕; 楊 応華; 柳川 洋二郎; 片桐 成二; 永野 昌志
  日本獣医学会学術集会講演要旨集, 2016年08月, (公社)日本獣医学会, 英語
  2016年08月 - 2016年08月
• 牛卵巣内胞状卵胞数と初期胞状卵胞由来卵子顆粒層細胞複合体の性ステロイドホルモン産生能の関係
  坂口 謙一郎; 谷田 孝志; 永井 克尚; 楊 応華; 柳川 洋二郎; 片桐 成二; 永野 昌志
  日本獣医学会学術集会講演要旨集, 2016年08月, (公社)日本獣医学会, 日本語
  2016年08月 - 2016年08月
• 卵胞膜細胞と共培養した牛卵母細胞-顆粒膜細胞複合体の増殖、ステロイド産生とその後の発生能(Growth, steroidogenesis and subsequent developmental competence of bovine oocyte-granulosa cell complex co-cultured with theca cells)
  楊 応華; 菅野 智裕; 坂口 謙一郎; 柳川 洋二郎; 片桐 成二; 永野 昌志
  日本獣医学会学術集会講演要旨集, 2016年08月, (公社)日本獣医学会, 英語
  2016年08月 - 2016年08月
• 北海道内における乳牛への性選別精液使用が後継牛生産と母牛の生存率に与える影響
  菅野 智裕; 萩原 精一; 伊藤 純一; 廣田 和久; 片桐 成二; 永野 昌志
  北海道獣医師会雑誌, 2016年08月, (公社)北海道獣医師会, 日本語
  2016年08月 - 2016年08月
• 卵胞刺激ホルモンの尾椎硬膜外腔内単回投与が黒毛和種牛の体内・体外胚生産に及ぼす影響
  坂口 謙一郎; 出田 篤司; 土屋 加那美; 真方 文絵; 小牧 春菜; 佐藤 正明; 酒井 伸一; 馬塲 貴大; 柳川 洋二郎; 永野 昌志; 片桐 成二; 小西 正人
  北海道獣医師会雑誌, 2016年08月, (公社)北海道獣医師会, 日本語
  2016年08月 - 2016年08月
• 凍結前精液の一時保存方法および冷却方法が融解後のマカク属精子の性状に与える影響
  栁川洋二郎; 杉本幸介; 菅野智裕; 高江州昇; 印藤頼子; 兼子明久; 木下こづえ; 今井啓雄; 岡本宗裕; 片桐成二; 永野昌志
  Cryopreservation Conference 2014, 2015年10月, 日本語
  2015年10月 - 2015年10月
• 牛の卵子品質と卵巣内卵胞数の関係 体内および体外発育卵子を用いた予備的検討
  永井 克尚; 杉山 ちさと; 楊 応華; 柳川 洋二郎; 片桐 成二; 永野 昌志
  The Journal of Reproduction and Development, 2015年09月, 日本繁殖生物学会, 日本語
  2015年09月 - 2015年09月
• ニホンザルにおける電気刺激時の電圧が精子採取に与える影響および精子凍結保存法の改善について
  杉本 幸介; 柳川 洋二郎; 菅野 智裕; 高江洲 昇; 兼子 明久; 印藤 頼子; 岡本 宗裕; 片桐 成二; 永野 昌志
  日本獣医学会学術集会講演要旨集, 2015年08月, (公社)日本獣医学会, 日本語
  2015年08月 - 2015年08月
• エゾシカにおけるPAGを用いた早期妊娠診断方法の検討
  柳川 洋二郎; 宮澤 千鶴; 松浦 友紀子; 下鶴 倫人; Noelita Melo de Sousa; Beckers Jean-Francis; 片桐 成二; 坪田 敏男
  北海道獣医師会雑誌, 2009年08月, (公社)北海道獣医師会, 日本語
  2009年08月 - 2009年08月
• マウス胞状卵胞由来卵母細胞の成熟培養時の基礎培地と気相中の酸素濃度が減数分裂の進行と発生能に及ぼす影響
  古山 敬祐; 片桐 成二; 高橋 芳幸
  The Journal of Reproduction and Development, 2008年08月, (一社)日本繁殖生物学会, 日本語
  2008年08月 - 2008年08月
• マウス卵子の成熟培養時の酸素濃度と培養時間が核成熟動態と発生能に及ぼす影響
  檜垣彰吾; 岸昌生; 永野昌志; 片桐成二; 高橋芳幸
  J Reprod Dev, 2007年09月25日, 日本語
  2007年09月25日 - 2007年09月25日
• マウス前胞状卵胞の体外培養とガラス化保存
  岸昌生; 永野昌志; 檜垣彰吾; 片桐成二; 高橋芳幸
  日本生殖医学会雑誌, 2007年04月20日, 日本語
  2007年04月20日 - 2007年04月20日

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• 1996年01月 - 現在
  日本繁殖生物学会
• 1996年01月 - 現在
  日本獣医学会
• 日本生殖医学会

• 牛子宮での上皮成長因子異常におけるToll様受容体4活性化の意義と治療への応用
  科学研究費助成事業
  2023年04月01日 - 2028年03月31日
  片桐 成二; 柳川 洋二郎; 杉浦 智親; 奥山 みなみ; 平山 博樹; 永野 昌志; 田上 貴祥
  日本学術振興会, 基盤研究(A), 北海道大学, 23H00353
• 受胎に必要な免疫制御に精漿が果たす役割とリンパ球の働きに関する研究
  科学研究費助成事業
  2024年04月01日 - 2027年03月31日
  奥山 みなみ; 片桐 成二; 杉浦 智親; 河野 康志
  日本学術振興会, 基盤研究(C), 大分大学, 24K09212
• 牛の精漿蛋白質による子宮機能調節機序の解明と受胎性改善技術への応用
  科学研究費助成事業 基盤研究(A)
  2019年04月01日 - 2024年03月31日
  片桐 成二; 柳川 洋二郎; 田上 貴祥; 平山 博樹; 杉浦 智親; 永野 昌志; 奥山 みなみ
  牛の低受胎（リピートブリーディング）の原因の1つとされる子宮での上皮成長因子（Epidermal growth factor, EGF）の濃度異常を解消し、受胎性を回復させる効果を持つと考えられる精漿タンパク質の1つがオステオポンチンである。今年度は、このオステオポンチンを遺伝子組換えタンパク質として調製してEGF濃度の低下がみられるリピートブリーダー牛への投与を行い、その効果を検証した。また、オステオポンチンを豊富に含む生乳からもオステオポンチンを調製し、同様に効果を検証した。
  組換えタンパク質は、大腸菌をベクターとして調製し、牛のオステオポンチンcDNAの塩基配列をもとに大腸菌ベクターに合わせたコドンの最適化を行った。予備的検討の結果からオステオポンチンの投与量は1 mgとし、発情日の人工授精実施後に腟深部に投与した。乳中オステオポンチンはイオン交換クロマトグラフィーにより調製し、組換えタンパク質と同様に1 mgを腟内に投与した。
  その結果、いずれのオステオポンチンも50%から60％のリピートブリーダー牛で子宮でのEGF濃度異常を解消した。治療後のEGF濃度正常化率には両群間で差異はみられなかったが、治療処置3日後の子宮内膜EGF濃度は組換えタンパク質を投与した群で高かった。遺伝子組換えオステオポンチンを投与した牛では、多くがEGF濃度の正常範囲の高い領域を示したのに対し、乳中オステオポンチンを投与した群では、EGF濃度は異常値（低値）から連続して正常範囲内の全域に広く分布する傾向がみられた。
  両オステオポンチンによる治療効果には、ホルモン製剤によるEGF濃度異常牛の治療でみられる農家あるいは牛群間での差異はみられず、全ての牛群でほぼ同等の効果がみられた。
  日本学術振興会, 基盤研究(A), 北海道大学, 19H00964
• 乳牛の低受胎対策技術の実行可能性検証事業
  令和3年度日本中央競馬会畜産振興事業
  2021年04月 - 2024年03月
  栁川洋二郎;田上貴祥;
  日本中央競馬会, 研究開発事業, 北海道大学大学院獣医学研究院, 研究代表者
• 精漿による子宮機能調節作用を利用した受胎促進技術の開発
  科学研究費助成事業 基盤研究(B)
  2016年04月01日 - 2019年03月31日
  片桐 成二; 柳川 洋二郎; 藤井 貴志
  本研究では不妊牛に見られる子宮での上皮成長因子（EGF）異常を解消する精漿中の有効成分を同定し、同定した蛋白を用いて投与を行うプロトコールを開発した。また、精漿によるEGF発現正常化の機序にリンパ節でのサイトカイン発現の変化が関与することを示した。さらに、肥満牛におけるEGF発現異常と牛の代謝状態の関係を検討し、EGF発現異常と糖負荷への反応性低下および血中テストステロン濃度増加とがこの病態に関係することも明らかにした。併せて子宮でのEGF発現異常による不妊症の経済的損失とその治療による経済効果を試算してモデル農場による本異常の治療効果がもたらす経済効果を試算し公表した。
  日本学術振興会, 基盤研究(B), 北海道大学, 16H05032
• 乳牛の低受胎対策新規技術開発事業
  平成29年度日本中央競馬会畜産振興事業
  2017年04月 - 2019年03月
  永野昌志; 栁川洋二郎; 田上貴祥; Su Thanh Ling
  日本中央競馬会, 研究開発事業, 北海道大学大学院獣医学研究院, 研究代表者
• 牛精漿中に含まれる子宮機能調節蛋白の同定とその作用経路の解析
  科学研究費助成事業 基盤研究(C)
  2011年 - 2013年
  片桐 成二
  腟内に投与した牛の精漿が子宮機能を調節し、受胎性を改善する機序を明らかにするため、精漿のシグナルが子宮に伝達される経路を調べた。その結果、精漿のシグナルはリンパ系路を介して内腸骨および深鼡径リンパ節に運ばれ、リンパ節でのサイトカイン環境を変化させることにより、子宮に伝達されることを示した。また、精漿中の蛋白質を分離・精製することにより、オステオポンチン類似の蛋白質に精漿による子宮機能調節効果のあることを示した。
  日本学術振興会, 基盤研究(C), 酪農学園大学, 研究代表者, 23580446
• 国際標準プロトコールによる乳牛における妊娠喪失の発生状況解析
  科学研究費助成事業
  2010年 - 2011年
  片桐 成二; GAUTAM Gokarna
  平成23年度の研究では、子宮内膜炎の後遺として生じる子宮内膜の組織学的変化を非侵襲的、かつ客観的に評価する指標として、PCR法によりいくつかの分子マーカビの発現を調べるとともに、超音波検査により子宮内膜の厚さを評価し、臨床所見および予後との関連を検討した。その結果、子宮内膜生検材料を用いた細胞診による多核白血球の出現率と発情後3および7日目の子宮内膜におけるサイトカイン(IL-4/IL-8)の発現比に高い相関(r=0.76)がみられた。一方、IL-4/IL-8の発現比が高かった牛の多くは炎症治癒の過程が速やかで(P<0.01)、かつその後の受胎成績は比較的良好であった。このことから、IL-4/IL-8比を含め、関連する他の分子マーカー発現から子宮内膜炎の予後に関する情報の得られることが分かった。一方、子宮内膜炎が治癒し、細胞診では炎症が認められないにも関わらず妊娠しない牛(分娩後180日以上)では、同時期の正常牛に比べて子宮内膜が薄く、子宮腺の発達が悪かった。とくに、分娩後に産褥性子宮炎を発症した牛および長期間(6週間以上)子宮に炎症の持続した牛では、対照牛に比べ発情期の子宮内膜の厚さに差異はみられなかったが、黄体期の子宮内膜の厚さが有意に減少していることが分かった。そこで、発情期および黄体期の子宮内膜の厚さおよび卵巣由来の性ステロイドホルモンおよびそのレセプター発現を調べたところ、血中ホルモン濃度には差異は見られなかったが、発情期の子宮内膜組織中のエストロジェンレセプター濃度(組織重量あたり)および黄体期の子宮内膜中のプロジェステロンおよび同レセプター濃度が対照牛に比べ低いことが明らかになった。以上のことから、子宮内膜の炎症が消失した後も長期間にわたって受胎しない牛には、子宮内膜炎発症中のサイトカイン発現および炎症消失後の内分泌因子の動態に特徴のあることが明らかとなった。これらの成果は、子宮内膜炎牛の治療方針決定および予後の推測に重要な情報であり、今後どの牛を、どの時期に治療し、どの時期に淘汰を決定するかなどの指標を提供することにつながるものである。
  日本学術振興会, 特別研究員奨励費, 酪農学園大学, 10F00112
• 高泌乳牛・低受胎における卵子成熟精動態の解明
  科学研究費助成事業 基盤研究(C)
  2009年 - 2011年
  高橋 芳幸; 片桐 成二; 永野 昌志
  現代の高泌乳牛にみられる繁殖性低下の原因となる卵子の成熟・受精の動態の特性・異常について検討、排卵直前の成熟卵子微細構造の特徴と排卵時期が確認され、体内における精子移送・貯蔵時間、排卵卵子の老化時期を推定できた。また、体外成熟卵子を用いて発生能獲期・喪失期の特徴を捉えるとともに、初期胞状卵胞卵子の個別発育培養法を開発した。さらに、腟温変動を指標にした排卵時期と異常排卵の予知法、精漿成分投与による低受胎牛の治療法を開発した
  日本学術振興会, 基盤研究(C), 北海道大学, 21580339
• 国際標準プロトコールによる高産乳牛における妊娠喪失発生状況の解析
  科学研究費助成事業 基盤研究(C)
  2008年 - 2010年
  片桐 成二
  乳牛の不妊原因を特定するための診断および研究手法の標準化を実現するため、EUおよび北米の研究者との国際共同研究により、妊娠が中断する時期を特定するための国際標準プロトコールを開発した。また、この標準プロトコールを用いて実施した予備調査の結果から、わが国と海外の乳牛における胚死滅発生時期および頻度の違いを明らかにし、わが国が独自で開発し、重点的に実施しなければならない不妊症対策の領域を明らかにした。
  日本学術振興会, 基盤研究(C), 酪農学園大学, 20580350
• 牛ウイルス性下痢ウイルス感染症の清浄化対策:コホート研究によるリスク分析
  科学研究費助成事業 基盤研究(B)
  2006年 - 2009年
  田島 誉士; 門平 睦代; 片桐 成二; 小沼 操; 片桐 成二; 小沼 操
  牛ウイルス性下痢ウイルス(BVDV)感染経路の分析ための疫学調査を、バルク乳検査によって陽性となった農家と陰性であった農家を無作為に抽出して実施した。分離ウイルスの分子系統樹解析結果からは、局地的に同一のBVDVの感染によって流行が生じている危険性が高いことが示された。また、各種疫学情報を各方面から入手し、リストアップされた因子についての危険度を統計学的にリスク分析した。その結果、牛の導入、牛舎内へのカラスや猫の侵入、などいくつかの危険因子が抽出された。(221 文字)
  日本学術振興会, 基盤研究(B), 北海道大学, 18380184
• 子宮での細胞増殖因子発現異常検出によるリピートブリーダー牛の診断および治療法開発
  科学研究費助成事業 基盤研究(C)
  2003年 - 2005年
  片桐 成二
  酪農業に重大な経済被害をもたらすリピートブリーディングの対策を講じるため子宮機能異常による不妊牛の摘発および治療法を検討した。まず、子宮における主要な増殖因子とサイトカインの周期的変動を調べた。そのうち上皮成長因子(epidermal growth factor, EGF)は発情後2-4および13-14日目に明瞭なピークを持つ周期的変動を示し、リピートブリーダー牛の約70%ではこれらのピークが消失していることを明らかにした。また、この異常は治療処置を行わなければ持続し、治療処置により受胎したリピートブリーダー牛の80〜90%では、妊娠に先立ちEGF発現が正常化していることも明らかにして、EGF発現異常がリピートブリーダー牛の不妊原因の一つであることを示した。次いで、EGF濃度異常の治療法を検討し、リピートブリーダー牛に対しプロジェステロン徐放剤と高用量(5mg)の安息香酸エストラジオールを組み合わせた治療を施すと約70%の牛でEGF発現が正常化し、その内70-80%の牛は治療後2回までの授精で受胎することを示し、効果的な治療法開発に成功した。一方、授精待機牛においてはEGF発現が受胎性の指標となることを示し、子宮内膜EGF濃度測定を受精卵移植のレシピエント選抜に応用することで受精卵移植後の受胎率が向上することを示した。また、分娩後の子宮におけるEGFの周期的変動が回復する時期とその異常を来す機序を明らかにするため、分娩後の子宮内膜でのEGF発現に影響を及ぼす因子を調べた。その結果、EGFの周期的変動回復には少なくとも8日以上の黄体期の出現が必要であることが明らかとなり、産褥期に短い間隔で排卵を繰り返す牛および子宮回復前に長い黄体期の出現した牛ではEGF発現異常の頻度が高まることが示唆された。
  日本学術振興会, 基盤研究(C), 北海道大学, 15580284
• ウシ卵胞発育および排卵障害機構解析モデル(卵胞体外培養法)の開発
  科学研究費助成事業 基盤研究(B)
  2001年 - 2003年
  高橋 芳幸; 永野 昌志; 片桐 成二
  ウシの卵胞発育および排卵障害の実態を把握するとともに、その機構を体外で解析できる卵胞培養法の開発を目的として研究を行った。
  まず、分娩後の乳牛の卵胞発育動態を調べた結果、卵胞発育ウェーブは分娩後4〜6日目頃から再開され、約半数のウシでは初回優勢卵胞が排卵せずに卵胞発育ウェーブを繰り返し、初回排卵の後の卵巣周期が短くなることが分かった。また、初回卵胞発育ウェーブの発現と分娩前後の血中卵胞刺激ホルモン(FSH)濃度を調べた結果、初回排卵の遅いウシでは分娩後の最初のFSH分泌が遅いために卵胞発育ウェーブの発現が遅延することが明らかになった。さらに、超音波誘導経膣採卵技術に改良を加えて分娩後早期の卵胞内卵子の受精能を調べた結果、妊娠末期に発育を停止していた卵胞に由来する卵子でも正常な発生能を保有していることも明らかになった。
  卵胞培養法については、まず、マウス卵胞をモデルにして検討した結果、メンブラン・インサートを用いた培養法が優れていることを突きとめ、その培養法を用いてガラス化保存した前胞状卵胞に由来するマウス産子を世界で初めて得ることができた。また、インサート内で培養した前胞状卵胞の発育と機能を調べた結果、80%以上が成熟卵胞へ発育し、その約70%は人絨毛性性腺刺激ホルモン処理によって排卵し、かつ排卵卵子の約50%が胚盤胞へ発育することが確認された。さらに、培養卵胞を用いて顆粒層細胞におけるトランスフォーミング増殖因子の発現が卵胞の発育にとって重要な役割を果たしていることも解析することができ、この培養法が卵胞発育や排卵の障害機構の解析モデルとして利用可能なことも実証された。また、ウシの卵胞はコラーゲン溶液に包埋して培養した結果、一次卵胞の発育と初期胞状卵胞由来卵子の成熟が確認された。
  日本学術振興会, 基盤研究(B), 北海道大学, 13460136
• ウシの子宮内細胞増殖因子およびレセプターの発現異常による着床不全に関する研究
  科学研究費助成事業 奨励研究(A)
  1999年 - 2000年
  片桐 成二
  牛の卵巣および子宮に生理活性物質を投与するシステム(手術、カニュレーション法など)を検討した。その結果、卵巣動脈および子宮動・静脈を介して2〜3発情周期にわたり持続的または断続的に生理活性物質を投与でき、子宮静脈および卵巣動・静脈からの連続採血も可能なシステムを開発できた。また、この状態で牛を妊娠させ、授精後30〜45日目まで妊娠の維持が可能であることを確認した。
  上記システムを用い、子宮静脈および卵巣動脈内にプロスタグランジン(PG)F_<2α>とPGE_2を種々の濃度で組み合わせて投与した結果、PGF_<2α>は一過性大量投与よりも、少量反復投与により、より確実に黄体退行を誘起することを確認した。さらに、PGF_<2α>単独の投与に比べ低濃度のPGE_2を同時に投与することにより、確実で急速な黄体退行を誘起できることを明らかにした。
  上記試験と平行して、臨床の現場において原因が特定できなかった繁殖障害牛を中心に、発情周期内での子宮内膜における上皮成長因子(EGF)およびそのレセプターの発現と、子宮内膜でのEGF機能について検討した。不妊原因の精査後、リピートブリーダー牛と診断された牛では、EGFレセプター発現量の発情周期内変化に異常はみられないが、多くの例(約80%)で子宮内膜EGF濃度(遺伝子およびタンパク量)の周期的な変化が失われていることを明らかにした。発情後14〜17日目の対照牛からバイオプシーにより採取した子宮内膜組織では、EGFがPGF_<2α>/PGE_2産生量比を抑制するのに対し、リピートブリーダー牛から得られた材料ではEGFによるPGF_<2α>/PGE_2産生量比抑制効果の失われていることを明らかにした。
  以上の結果から、リピートブリーダー牛ではEGFの発現および機能の異常により子宮でのPG産生調節機構に異常がみられ、黄体機能を維持できないため胚の死滅や着床不全により不妊となることが示唆された。
  日本学術振興会, 奨励研究(A), 北海道大学, 11760188
• 牛の核移植(クローン)技術の実用化に関する総合的研究
  科学研究費助成事業 基盤研究(B)
  1998年 - 2000年
  高橋 芳幸; 森安 悟; 永野 昌志; 片桐 成二; 岸 昌生
  本研究では、割球および体細胞を用いた牛の核移植について検討を加えるとともに、卵子の凍結や卵胞培養も含めたクローン技術に関する総合的な研究を実施した。まず、割球を用いた核移植技術について種々の検討を加えた結果、桑実胚の割球を用いた核移植では、予め活性化処理を施した卵子を除核する効率的な除核方法を開発した。また、体外受精由来胚の割球から作出されなクローン胚の受胎率が体内受精由来胚を用いて作出した核移植胚に比べて低いことや、双子および四つ子のクローン牛の斉一な発育と雌牛の妊孕性が確認された。
  体細胞核移植では、乳腺上皮細胞や卵管上皮細胞を用いて作出した核移植クローン胚の産子への発生が確認された。また、体細胞の培養処理やレシピエント卵子との細胞周期の組合せなどを検討し、飢餓培養あるいはコンフルエント培養処理した卵丘や繊維芽細胞の約95%がG0/G1期に同調しており、M期の除核卵子と融合させて作出した核移植胚の発生率が高いことが分かった。しかし、S期の除核卵子はS期に同調させた体細胞と融合させてもほとんど発生しないことも分かった。さらに、牛の核移植の実験で得られた知見をもとに豚の体細胞核移植胚を作出し、胚盤胞への発生を確認できた。
  前胞状期卵胞をレシピエント卵子の供給源として活用する技術の開発では、牛の二次卵胞の採取・培養法と初期三次の発育培養法について検討し、初期三次卵胞の培養によりMII期の卵子の得られることや、二次卵胞の採取・培養法ならびに生存卵胞の選抜法に関する基礎的知見も得た。また、前胞状卵胞の低温保存法についてはマウスの卵胞を用いて検討を加え、ガラス化保存した前胞状卵胞由来の卵子が体外受精後に胚盤胞へ発生することが判明した。
  日本学術振興会, 基盤研究(B), 北海道大学, 10556058