Studies on a Scorpaenous fish Sebastiscus marmoratus CUVIER et VALENCIENNES―VI Electron-Microscopic Study of Spermatogenesis
摘要
The Spermatogenesis and the structure of spermium of marine ovoviviparous teleost fish, Sebastiscus marmoratus, was observed by electron microscope. The author had formerly studied this problem by optical microscope, but the division of spermatozoa was observed erroneously in that study. During the sexual resting period, there is no spermatozoon in the seminiferous tubules of this fish, but in June the spermiogonia appear from the basement membrane under the seminiferous epithelium. The spermato-genesis of this fish is classified into two periods, one is multiplying period and the other is developing periods. In maltiplying period, the spermiogonium which appears on the basement membrane is divided repeatedly ane grow into many spermatozoa in a cyst. A cyst originates from a spermiogonium, and the growing stage of the spermatozoa in a cyst is quite equal, but different from that of the spermatozoa in any other cyst within a seminiferous tubule. During the developing period after the multiplying period, the nuclear contents of the spermatozoa in the cyst are granulated and all the granules are collected at one end of the nucleus and finally become the sperm head. There is no head cap in the sperm head of this species. And then the mitochondorias in the protoplasm gather at one end and when the nuclear contents begin to grow in granular condition, the tail flagella appears from the nucleus and is surrounded by the mitochondorias. The tail flagella grows longer along with the progress of nucleus (sperm head). The number of mitochondorias around the tail flagella of this species is less than that of mammals. The mitochondorias are not in immediate contact with the tail flagella but packed by the mitochondorial sheath at the surroundings of the base of tail flagella. The tail flagella consists of a central pair of tail axial fibril and nine pairs of fibril surrounding it.!?1. The testes of Sebastiscus marmoratus, a marine ovoviviparous teleost fish, in the reproductive s