条纹锯鮨精子超微结构及其入卵过程的电镜观察

Observations on the Spermatozoon, Egg and Fertilization Process of Centropristis striata Using the Electronic Microscopic Technique

中文关键词: 条纹锯鮨  精子  卵子  精子入卵  电镜

英文关键词: Centropristis striata  Spermatozoon  Eggs  Fertilization process  Electron microscopy

中文摘要:

      采用扫描和透射电镜技术对自然成熟的条纹锯鮨精子、卵子及精子入卵过程进行观察。观察结果显示，其精子由头部、中段和尾部三部分组成：头部主要由细胞核构成，无顶体结构；中段由线粒体、中心粒复合体(近端中心粒和基体)、袖套组成；尾部主要由轴丝组成，外部包裹质膜，轴丝为典型的“9+2”结构。卵子表面分布纵横交错的网纹，均匀分布着大小不一的微小孔，在卵壳的动物极精孔区的中央有一个受精孔。在授精后10 s即可见到精子通过受精孔进入卵子，刺激卵子发生形态变化封闭受精孔，阻止其他精子入卵，60 s可见受精孔完全封闭。

英文摘要:

      To explore the fertilization mechanism of Centropristis striata and improve the fertilization rate, the ultrastructure of spermatozoon and egg and the fertilization process were observed using the scanning electron microscope (SEM) and transmission electron microscope (TEM). The results showed that the sperm of C. striata was mainly composed of the following three parts: 1) head; mainly consisted with nucleus and without the acrosomal structure; 2) midpiece; consisted with mitochondrion, centriolar complex (including proximal centriole and matrix) and sleeve structure; and 3) tail; consisted with axoneme that is surrounded by plasma membrane. The axoneme of C. striata was consistent with the typical “9+2” structure in most fish. The eggs were spherical, colorless, and transparent with the diameter at (0.950±0.039) mm, which belonged to pelagic eggs. A big grain of oil ball (0.182 ± 0.011mm in diameter) was observed in the egg. Overlapping curves were observed on the surface of the eggs, on which the tiny holes with different sizes (0.246±0.103 µm) were evenly distributed. A completely-opened fertilization hole was in the central part of the funneled area at the animal pole. The shell of the egg included plasma membrane, vitelline membrane and shell membrane. The shell was filled with cytoplasm. The fertilization process of C. striata was short. The sperm penetrated into the egg through the micropyle in 10 seconds after insemination. The morphological feature of the fertilized egg changed after that, and the fertilization cone and fertilization plug were observed. Finally, about 60 s after insemination, the fertilization hole closed to prevent the penetration of other sperms. This study may provide theoretical foundation to improve the fertilization rate of C. striata artificial breeding.