Spermatogenesis, Serum Testosterone Levels and Immunolocalization of Steroidogenic Enzymes in the Wild Male Japanese Black Bear (Ursus thibetanus japonicus)

Journal of Veterinary Medical Science

Toshio TSUBOTA¹  Tetsuma MURASE¹  Tsukasa OKANO¹ 

[1] United Graduate School of Veterinary Medicine, Gifu University

关键词: Japanese black bear;    spermatogenesis;    steroidogenic enzyme;    testosterone;    Ursus thibetanus japonicus;   

DOI  :  10.1292/jvms.65.1093

学科分类：兽医学

来源: Japanese Society of Veterinary Science

【 摘 要 】

References(29)Cited-By(17)Twenty-one wild male Japanese black bears (Ursus thibetanus japonicus) were captured in the summer-autumn of 1998-2000 in the vicinity of Neo Village, Gifu Prefecture. Testes were measured, and testicular samples were biopsied and observed histologically. Four steroidogenic enzymes, i.e., cholesterol side-chain cleavage cytochrome P450 (P450scc), 3β-hydroxysteroid dehydrogenase (3βHSD), 17-α hydroxylase cytochrome P450 (P450c17), and aromatase cytochrome P450 (P450arom) were immunolocalized. Serum testosterone concentrations were measured by radioimmunoassay. Testis size changed little from 1-3 years of age, increased rapidly at 4 years, and attained its peak at 5 years. Serum testosterone concentrations ranged from 0.05 to 1.78 ng/m l, and the mean ± standard deviation was 0.43 ± 0.48 ng/ml. Age of sexual maturation in wild male Japanese black bears was estimated to be 3-4 years. Seasonal changes in spermatogenesis were obvious; active in June, July and August, degenerated by September. Leydig cells, Sertoli cells and germ cells have the capability of synthesizing androgen, and Leydig cells, Sertoli cells, spermatids and spermatogonia have the capability of synthesizing estrogen in Japanese black bears.

【 授权许可】

Unknown