An Electron Microscope Study of Spermiogenesis in the Japanese Eel, Anguilla japonica
摘要
Mter injeoting Synahorin, the fine struoture of spermatid differentiation in the Japanese eel, Anguilla japonica is studied.In telophase of the last maturation division the ohromatin material oondenses to form the nuoleus, followed by formation of nuolear envelope.The nuoleus rapidly grows in size, and oompared to early spermatid it inoreases about 28.9% in surface area by late spermatid stage, with the simultaneous transformation from oval to siokle shape.The nuoleus of early and middle stage spermatid generally shows the presenoe of one wall-less vaouole, whereas late spermatid has more than one.The only mitoohondrion, whioh is big and rounded, gradually moves down and enoiroles the flagellum to form middlepieoe.Sperm head is devoid of any aorosome, and the tail shows 9+0 pattern.