魁蚶精子发生的超微结构

利用透射电镜(TEM)技术观察了魁蚶精子发生过程的超微结构变化。结果表明:魁蚶精子发生经历了精原细胞、初级精母细胞、次级精母细胞、精子细胞和精子形成等过程,在精子形成中的主要细胞学事件包括顶体的发育、核形态变化及尾部的形成等。此过程中,前顶体颗粒聚集、融合,形成顶体囊,然后发育为圆锥形顶体;核的形态由圆形或卵圆形变为鼓形,核内染色质由团块状到颗粒状,再到高电子密度均质;线粒体聚集、融合、体积变大,迁移至核的后端,参与精子中段的形成。成熟精子由头部、中段及尾部组成,头部由顶体及核构成,中段由5个线粒体围绕远端中心粒组成,尾部为细长的鞭毛。研究亮点:魁蚶为我国重要的海产经济贝类之一,目前对其精子发生过程的超微结构未见研究报道。利用透射电镜技术观察了魁蚶精子发生过程中精子顶体的形成、核的形态建成等主要细胞学事件,探明了魁蚶精子属原生型,顶体物质的合成始于初级精母细胞时期,细胞核在精子发生过程中形态变化不大等问题,为蚶科精子发生机制的深入研究提供了参考。

Ultrastructure of spermatogenesis of Scapharca broughtoni

Ultrastructural changes during spermatogenesis of Scapharca broughtoni were investigated by transmission electron microscopy. Results showed that spermatogenesis in this species underwent successive stages of spermatogonium, primary spermatocyte, secondary spermatocyte, spermatid and spermatozoa. The changes during spermiogenesis mainly include acrosome development, morphological transformation of nucleus and formation of tail. In these processes, proacrosomal granules accumulated and fused into acrosomal vesicle and finally became a cone shaped acrosome. The nucleus changed from round or oval to tympaniform. The chromatin in nucleus changed gradually from agglomerate to granule and eventually became homogenous with high electron density. Mitochondria accumulated and fused with larger size. At the same time, they gradually moved to the nucleus posterior and participated in formation of the mid piece. Mature spermatozoon contained three parts: head, mid piece and tail. The head consisted of an acrosome and a nucleus. The mid piece comprised five mitochondria surrounding the distal centriole. The tail was a slender flagellum.