九孔鲍精子发生的超微结构

利用透射电镜观察九孔鲍（Haliotis diversicolor aquatilis）精子的发生过程。结果表明，九孔鲍精子的发生历经精原细胞、初级精母细胞、次级精母细胞、精细胞和成熟精子5个阶段。其中精细胞的分化可分为5期，主要特点为：Ⅰ期，一些高电子致密颗粒参与顶体的形成；Ⅱ期，核形态由椭圆形到近圆形，再逐渐拉长为长圆柱状；Ⅲ期，核染色质以颗粒状形式凝集，最后向高电子密度均质状态转变；IV期，线粒体逐步融合、体积增大和嵴发达；Ⅴ期，中心体移动及鞭毛形成，胞质逐渐减少。成熟精子为原生型，由头部、中段和尾部组成。通过观察精子发生过程中细胞形态结构的变化，分析了其演变规律，同时与软体动物的其他种类作了比较研究。

Ultrastructure of spermatogenesis of Haliotis diversicolor aquatilis

The ultrastructure of spermatid of Haliotis diversicolor aquatilis at different staqes was investigated by transmission electron microscopy.The results show that the spermatogenesis of H.diversicolor aquatilis includes following five stages:spermatogonium,primary spermatocyte,secondary spermatocyte,spermatid and spermatozoon.Spermatogonium was ellipsoidal in shape and the cytoplasm had few mitochondria,few endoplasmic reticulum vesicles and electron dense granules.Nuclear membrane was clear and chromatin was little.Primary spermatocyte and its nucleus still presented ellipsoidal shape or spherical shape;the cytoplasm became dense and mitochondria became more and larger,and Golgi body developed very well and electron dense granules became more.The clearance between nuclear membrane was larger and number of chromatin increased.At the stage of secondary spermatocyte,cell and nucleus approximately took on spherical shapes.The electron dense granule began to gather at the posterior of cell;the standard "9+2" microtubular structure could be observed in the cytoplasm;part of nuclear membrane obviously expanded to form nuclear membrane vesicle,and chromatin condensed to dense lump.The spermatid was the most complexly changing stage during the whole process of spermatogenesis,whose characteristics as follows:acrosome was formed from proacrosomal vesicle fused with vesicles secreted by Golgi body and some electron dense granulse in cytoplasm,and the form of their nucleus changed from ellipsoidal to spherical,and then gradually elongated and finally became long cylindrical.Chromatin condensed in granular pattern,and then turned to home geneous and even higher electron-density till the formation of spermatozoon nucleus.Mitochondria gradually fused and increased in size and ridge developed,centriole shifting and flagellar formation,cytoplasmic sloughing.Mature spermatozoon canbe chssified into primitive type,composed of three regions:head,middle piece and tail.During the spermatogenesis,the morphological changes of cells are also discussed and compared with spermatogenesis of other mollusks.Journal of Fishery Sciences of China,2006,13(6):878-884]