摘要
通过扫描电镜和透射电镜对经人工催产获得的日本鳗鲡(Anguilla japonica)精子、卵膜的超微结构以及受精过程进行了观察。实验观察到,除一般硬骨鱼类的精子特性外,日本鳗鲡精子有其独特的结构。精子头部为不规则的梨形,有背腹面之分。一个巨大的球形线粒体位于头部顶端。精子中段向后伸出一支根,支根位于袖套腔外精子的背侧,前端向精子头部线粒体方向延伸,支根的微管结构为"8+2"结构,并在精子入卵过程中起到切断鞭毛的作用。精子的尾部由鞭毛和鞭毛末端的结组成。鞭毛横切面呈圆形,无侧鳍,鞭毛微管结构为"9+0"结构。受精卵的整个表面密布着无规律延伸的脊、脊包围形成的窝和窝中的孔所组成的脊孔复合体,但无典型特征的受精孔。受精卵超薄切片观察发现,日本鳗鲡卵膜分为外层壳膜和内层卵黄膜。壳膜与卵黄膜间为卵周隙。壳膜只观察到放射带,未见透明带。放射带可分为三个亚层:最外层为脊孔复合体的脊,中间层为皱纹层,最内层为致密的平滑层。脊孔复合体的孔横穿整个放射带,在放射带内层形成一个乳突状结构。日本鳗鲡的卵膜不仅具有保护卵子的作用,而且还参与了受精。实验还通过扫描电镜观察了日本鳗鲡精子的入卵过程。观察结果认为:日本鳗鲡精子入卵过程可分为卵膜对精子的吸引、精子对卵膜的锚定、精核的进入和孔封闭等4个阶段。但由于研究只观察到受精过程中日本鳗鲡精子和卵膜的形态变化,因此对精子穿过卵膜的方式和特征等尚需做进一步的研究。整个受精过程为1min30s左右。此外,研究还探讨了日本鳗鲡精子结构的特殊性和受精过程的特殊性,为进一步突破日本鳗鲡人工育苗技术提供了理论依据。
This paper focus on the ultrastructure of sperm and egg membrane of Anguilla japonica,which was artificially induced by extraneous hormone,and an observation on the fertilization process by means of scanning electron microscope（SEM） and transmission electron microscope（TEM）,so as to provide theoretical basis for breaking through the artificial reproduction of Anguilla japonica furthermore.The results showed that the spermatozoa of Anguilla japonica was composed of head﹑middle piece and flagellum.The sperm head which divided into back side and dorsal side was in the shape of erose pear.An undee membrane wrapped the sperm head.There was great interspace between the undee membrane and karyon.The karyon filled with electron density substance nearly occupied the whole space of the sperm head.Many nuclear vacuoles in different size irregularly distributed in the karyon.One large round mitochondrion was in a cyst which was on the top of sperm head and had no acrosome.Middle piece of sperm which was wrapped up in an undee membrane connected with flagellum.Additionally,a rootlet lied dorsal side of spermatozoa threw out backward from the middle piece,forming ＂8＋2＂pattern.The rootlet front part of which extended to the mitochondrion could cut off the flagellum during fertilization process.There were many cytoplasma granules between the cytoplasma membrane and the karyon membrane.The sperm tail was composed of flagellum and tip of flagellum.The cross section of the flagellum which was composed of axoneme and microtube formed in a ＂9＋0＂pattern appeared to be round,no side fin.A great deal of ridge-hole complexes distributed on the surface of fertilized eggs,where no fertilization hole was found.Matured eggs were wrapped up in outer egg-shell membrane and inner vitelline membrane between which perivitelline space lied.Radiozone but no zone pellucida was found on egg-shell membrane.The radiozone was divided into three sublayers.Out layer formed with the ridge of ridge-hole complex.The middle layer was gauffer layer and the inner compact smooth layer.The hole of ridge-hole complex penetrated the whole radiozone and formed a mostoid structure at the bottom of the radiozone.Egg membrane not only protected eggs but participated in the fertilization process.The process of fertilization which happened pre and post 30 seconds after fertilization could divide into four phases：egg membrane attracting sperm;sperm anchoring on egg membrane;sperm karyon penetrating into egg membrane and holes on the surface closing.Only morphological changes of Anguilla japonica sperm and egg membrane were observed in this paper.The character and way of sperm penetrating into egg membrane need thorough research.
出处
《水生生物学报》
CAS
CSCD
北大核心
2010年第4期769-778,共10页
Acta Hydrobiologica Sinica
基金
国家十一五科技支撑计划(2006BADO3B08-04)
中央级公益性科研院所基本科研业务费专项资金(中国水产科学研究院淡水渔业研究中心)资助
关键词
日本鳗鲡
精子
受精卵
受精过程
超微结构
Anguilla japonica
Spermatozoa
Fertilized eggs
Fertilization process
Ultrastructure
