Japanese Eel: A Model for Analysis of Spermatogenesis
Japanese Eel: A Model for Analysis of Spermatogenesis
复制标题
DOI：
10.2108/zsj.18.1055
复制
发表时间：
2001-11
期刊：
影响因子：
--
通讯作者：
T. Miura;C. Miura
中科院分区：
文献类型：
--
作者：
T. Miura;C. Miura
摘要日本鳗鲡具有两个有利于研究精子发生机制的特征。一种是通过外源性促性腺激素注射人工诱导从精原细胞增殖到精子发生的完整过程的可能性，另一种是在体外睾丸器官培养或生殖支持细胞共培养系统中诱导这一过程的可能性。利用鳗鱼系统，我们分析了精子发生的调控机制。日本鳗鲡精子发生的全过程受多种性类固醇激素的调控。精原干细胞更新由雌二醇-17 β（脊椎动物中的天然雌激素）促进。硬骨鱼类的主要雄激素11-酮睾酮可诱导精原细胞增殖。IGF-I是11-酮睾酮启动精子发生所必需的。11-酮睾酮的作用是由其他因子介导的，例如由支持细胞产生的激活素B。虽然11-酮睾酮也诱导减数分裂和精子发生，但这些过程的控制机制尚不清楚。精子发生后，未成熟的精子经历精子成熟，从而变得能够受精。精子成熟受17α，20 β-二羟基-4-异戊烯-3-酮（17α，20 β-DP）的调节，它是硬骨鱼类的孕激素。17α，20 β-DP直接作用于精子，激活精子中存在的碳酸酐酶。这种酶的激活导致精浆pH值升高，使精子能够运动。
Abstract The Japanese eel has two characteristics advantageous for the study of the mechanisms controlling spermatogenesis. One is the possibility of artificial induction of the complete process of spermato-genesis from spermatogonial proliferation to spermiogenesis by exogenous gonadotropin injection, and the other is the possibility of inducing this process in an in vitro testicular organ culture or germ-Sertoli cell coculture system. Using the eel system, we analyzed the control mechanisms of spermatogenesis. In Japanese eel, the whole process of spermatogenesis is regulated by several sex steroid hormones. Spermatogonial stem cell renewal is promoted by estradiol-17β (the natural estrogen in vertebrates). Spermatogonial proliferation can be induced by 11-ketotestosterone, the main androgen in teleost. IGF-I is necessary for the action of 11-ketotestosterone in the initiation of spermatogenesis. The action of 11-ketotestosterone is mediated by other factors, such as activin B, produced by Sertoli cells. Although 11-ketotestosterone also induce meiosis and spermiogenesis, the control mechanisms of these processes are not clear. After spermiogenesis, immature spermatozoa undergo sperm maturation, thereby becoming capable of fertilization. Sperm maturation is regulated by 17α,20β-dihydroxy-4-pregnen-3-one (17α,20β-DP), which is progestogen in teleosts. The 17α,20β-DP acts directly on spermatozoa to activate the carbonic anhydrase existed in the spermatozoa. This enzymatic activation causes an increase in the seminal plasma pH, enabling spermatozoa to motile.