细鳞鱼精巢超微结构和精子发生

ULTRASTRUCTURE OF THE TESTIS AND SPERMATOGENESIS IN BRACHYMYSTAX LENOK (PALLAS)

细鳞鱼Brachymystax lenok(Pallas)精巢为叶型;支持细胞(Sertoli cell)和Leydig细胞具有典型内分泌细胞的一些结构特征;A型精原细胞的细胞器是区域性分布,精原细胞线粒体的发育与拟染色质 (chromatoid bodies)有关;生精细胞(spermatogenic cell)核膜孔由均匀排布最终演变为区域性聚集。重复注射绒毛膜促性腺激素(hCG)可促进雄鱼性成熟;精子质量受到多种因素的影响。

The fine structures of the testis and spermatozoon in Brachymystax lenok (Pallas) have been studied by transmission and scanning electron microscope. Brachymystax lenok (Pallas) has testicular structure of lobular type. The lobules contain numerous cysts around which is a layer of Sertoli cell. Inside each cyst, there arc many spermatogenic cells in synchronous stages. Both of Sertoli cell and Leydig cell possess some structrual characteristics of typical endocrine gland cell. There are numerous lipid droplets within Sertoli cell, and some of them are surrounded by concentric cisternae of smooth endophasmic reticulum. In Leydig cells located in interstitium, many smooth endoplasmic reticula and mitochondria are present. Containing some collagen fibers, the boundary cells form an uncompleted circumferential layer around the lobule periphery. The spermatogonia have been divided into two kinds of type. The spermatogonia A have very diffuse, homogeneous chromatin, one or two large nucleoli, and numerous chromatoid bodies. The organelles ar concentrated at local region within type A spermatogonia. The mitochondria have few cristae and are vesicular. In spermatogonia B, the mitochondria are elongate and have relatively more cristae. Chromatoid bodies relate to development of mitochondria. In young spermatids, the nuclear chromatin subsequently become to condense in the form of coarse granules, fibers and ribbonlike elements which eventually partly fuse together in the centre of nuclei. The condensed thick fibers appear to show a radiate orientation while the centriolar complex was definitively fixed in the implantation fossa. At the same stage, the nuclei elongate to form elliptic shape. The mitochondria polarized around the centriolar complex are finally organized into an annular mid-piece. During spermatoge-nesis, nuclear pores within spermatogenic cell undergo evolution of distribution from uniform to regional. Sperm quality is influenced by environmental factors and a higher dose of inducing spawning. It is supposed that induced spawning by repeated treatment with exogenous hormone may cause the Sertoli cell cyst to 'break' ahead of spermiation time, resulting in the spermatids released to lobular lumen in immature male fish.