Fu Su-Yan, Jiang Jian-Hu, Yang Wan-Xi, Zhu Jun-Quan
The Key Laboratory of Applied Marine Biotechnology by the Ministry of Education, College of Ocean, Ningbo University, Ningbo 315211, China.
The Key Laboratory of Applied Marine Biotechnology by the Ministry of Education, College of Ocean, Ningbo University, Ningbo 315211, China; Zhejiang Institute of Freshwater Fisheries, Huzhou, Zhejiang 313001, China.
Tissue Cell. 2016 Feb;48(1):49-62. doi: 10.1016/j.tice.2015.10.005. Epub 2015 Nov 26.
Testis development and ultrastructural features of spermatogenesis in Acrossocheilus fasciatus (Cypriniformes, Barbinae), a commercial stream fish, were studied using light and electron microscopy. The reproduction cycle in A. fasciatus testes is classified into six successive stages from Stage I to Stage VI. Based on an analysis of previous results, May to July can be confirmed as the best breeding season for A. fasciatus males. During this time, the A. fasciatus testes are in Stage V and the sperm in males is most abundant. In the first reproductive cycle, sexually mature male testes return to Stage III in October, subsequently overwintering at this stage. In the lobular-type testes of A. fasciatus, cystic type spermatogenesis occurs with restricted spermatogonia. All spermatogenic cells at different stages are distributed along the seminiferous lobules, which contain spermatogonia, spermatocytes, spermatids and spermatozoa. At the end of spermatogenesis, spermatogenic cysts open to release spermatozoa into the lobule lumen. Ultrastructural observation of A. fasciatus spermiogenesis reveals that electron-dense substances appear at the different stages of germ cells, from primary spermatogonia to secondary spermatocytes. We have termed these dense substances as "nuage" when free in the cytoplasm or adjacent to the nuclear envelope, while those close to the mitochondria are called inter-mitochondrial cement. The spermatozoa in A. fasciatus can be classified as type I due to the presence of nuclear rotation. Although the nuclear chromatin in the head of sperm was highly condensed, no acrosome was formed. The cytoplasmic canal, a common ultrastructural feature of Teleostei spermatozoa, was also present in the midpiece. In addition, numerous fused mitochondria were observed. The distal centriole and proximal centriole constituting the centriolar complex were oriented incompletely perpendicular to each other. The flagellum showed a typical 9+2 arrangement pattern. Conversely, our study on A. fasciatus yielded no information concerning the lateral fins although an enlarged saclike area was present at the end of some flagella.
利用光学显微镜和电子显微镜研究了经济鱼类条纹小鲃（鲤形目，鲃亚科）的睾丸发育及精子发生的超微结构特征。条纹小鲃睾丸的繁殖周期从第一阶段到第六阶段分为六个连续阶段。根据以往结果分析，5月至7月可确定为条纹小鲃雄鱼的最佳繁殖季节。在此期间，条纹小鲃睾丸处于第五阶段，雄性精子最为丰富。在第一个繁殖周期中，性成熟的雄鱼睾丸在10月回到第三阶段，随后在此阶段越冬。在条纹小鲃的小叶型睾丸中，精子发生为囊性，精原细胞受到限制。不同阶段的所有生精细胞沿生精小叶分布，生精小叶包含精原细胞、精母细胞、精子细胞和精子。精子发生结束时，生精小囊开放，将精子释放到小叶腔中。条纹小鲃精子形成的超微结构观察表明，从初级精原细胞到次级精母细胞，生殖细胞的不同阶段会出现电子致密物质。当这些致密物质在细胞质中游离或靠近核膜时，我们将其称为“云状小体”，而靠近线粒体的则称为线粒体间基质。由于存在核旋转，条纹小鲃的精子可分为I型。虽然精子头部的核染色质高度浓缩，但未形成顶体。细胞质管是硬骨鱼类精子的常见超微结构特征，也存在于中段。此外，观察到大量融合的线粒体。构成中心粒复合体的远端中心粒和近端中心粒彼此不完全垂直排列。鞭毛呈现典型的9+2排列模式。相反，尽管在一些鞭毛末端存在一个扩大的囊状区域，但我们对条纹小鲃的研究未获得有关侧鳍的信息。
