| Co-Investigator(Kenkyū-buntansha) |
KANAI Yoshiakira The University of Tokyo, Graduate School of Agricultural and Life Sciences, Professor, 大学院・農学生命科学研究科, 助手 (30260326)
HAYASHI Yoshihiro The University of Tokyo, Graduate School of Agricultural and Life Sciences, Professor, 大学院・農学生命科学研究科, 助教授 (90092303)
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| Budget Amount *help |
¥2,700,000 (Direct Cost: ¥2,700,000)
Fiscal Year 2003: ¥1,200,000 (Direct Cost: ¥1,200,000)
Fiscal Year 2002: ¥1,500,000 (Direct Cost: ¥1,500,000)
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| Research Abstract |
First, seasonal changes in spermatogenesis of Japanese lesser horseshoe bats (a hibernating) were examined by light microscopy. In march, the seminiferous tubules revealed almost no lumen. The seminiferous epithelium consisted of Sertoli ells and spermatogonia. In june, the seminiferous tubule gradually increased in diameter. Lumen was clearly seen. Spermatocytes were occasionally recognized. In August and October, active spermatogenesis was clearly observed. In December (hibernation period), spermatogenesis completely disappeard. The diameter of tuvules greatly decreased. In most cases, the seminiferous epithelium contained only Sertoli cells and spermatogonia. Second, as the preliminary step for hibernation experiments, we examined the influence of long and short photoperiods in testes of Syrian hamsters. Under a long photoperiod, active spermatogenesis was observed, whereas under a short photoperiod, spermatogenesis completely ceased. Immunohistochemistry detected Smad2 and Smad 3 i
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n the cytoplasm of spermatocytes in the active testes. In the regressed testes, both Smads were detected in the nucleus of spermatocytes. Third, morphological dynamics on spermatogenesis in Syrian hamsters exposed to both short photoperiod and low ambient temperature were examined. Male Syrian hamsters, kept in a long photoperiod, were transferred to a short fff (6L18D) and kept there for 13weeks to induce testicular regression Some hamsters were then transferred from the room at 23℃ to that at 5℃(5℃ group). Remaining hamsters were continuously kept at 23℃ (23℃group). As a result, a rapid recrudescence was observed in 23℃ group. At 2 weeks (total 15 weeks), pachytene spermatocytes appeared, at 4 weeks round spermatids were detected, and at 8 weeks spermatogenesis finally recomvered. While littl recrudescence was observed in 5℃group during the first several weeks. At 13 weeks (total 26 weeks), pachytene spermatocytes appeared and at 16weeks round spermatids were observed. It was not until 20 weeks that active spermatogenesis was recognized. Then, the changes in the proliferative and apoptotic activities in the seminiferous epithelium of 5℃ and 23℃ groups were examined. Although no significant difference in spermatogonia proliferative activity between 5℃ and 23℃ groups was confirmed, a notable increase in the rate of apoptosis was observed in 5℃ group compared with 23℃ group. Furthermore, this increase was more salient during the hibernation period. These findings suggest that cold ambient temperature causes the delay of testicular recrudescence and this delay arises from the increase of apoptotic activity but not the change in proliferative activity in spermatogonia in 5℃ group. Compared to cold ambient temperature causes the delya of testicular recrudescence and this delay arises from the increase of apoptotic activity but not the change in proliferative activity in spermatogonia in 5℃ group. Compared to cold ambient temperature, hibernation may be more dominant factor that stimulates the apoptotic activity to induce a recrudescent delay. Less
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