七带石斑鱼精子的超微结构

Ultrastructure of spermatozoa in Epinephelus septemfasciatus

利用透射电子显微镜技术研究了七带石斑鱼(Epinephelusseptemfasciatus)精子的超微结构,结果发现:七带石斑鱼精子由头部和尾部(鞭毛)两部分组成,没有明显的中片,头部前段无顶体,主要有高电子密度的球形细胞核,核中主要是致密的染色质,还分布有一些核泡,核外由核膜包围,将核与细胞质分隔开,核膜最前端紧贴质膜,核后端有植入窝,近端中心粒和中心粒间体位于其中。头部后端为袖套结构,由质膜包围的袖套结构延伸到后部,使整个头部呈椭球形,质膜后端沿鞭毛形成一个袖套腔,袖套结构中分布有中心粒复合体、线粒体以及囊泡等。精子细胞的细胞膜不光滑,呈现小的皱折。七带石斑鱼精子的尾部细长,紧接于头部细胞核,穿过袖套腔,通过基体与核紧密结合,中心粒复合体也位于此,且近端中心粒和远端中心粒呈钝角,鞭毛的轴丝由此形成,基体与鞭毛间的过渡区轴丝无中央微管,呈"9+0"型。尾部的主要结构为轴丝,其轴丝为典型的"9+2"结构,其起始端开始于前端基体,轴丝外仅有少许细胞质。

Ultrastructure of spermatozoa of E.septemfasciatus was investigated using transmission electron microscopes.The spermatozoa consists of two parts： the head and the tail（flagellum）,no mid-piece.The spermatozoa of E.septemfasciatus has no acrosome.A large spherical nucleus,covered with nuclear membrane,is located at the front part of the head and about its 1/3.The high electron density chromatin is the main components of nucleus,with several low electron density vesicles in it.There is little space between the plasma membrane and nuclear membrane at the front part of head.The implantation fossa is located in the posterior end of the nucleus.Proximal centriole and intercentriolar body are located in implantation fossa.The posterior end of the head is a large sleeve,which is about 2/3 of the head.The sleeve contains centriolar complex,several mitochondria and vesicles.At the mid-part of the sleeve,there is a sleeve carve,out of which the thin and long tail stretches.The tail with only a little cytoplasm is thin and long.The axoneme between the end of the base body and the head of the tail is ＂9＋0＂.The 9 doublet of the axoneme,the central structure of the tail,is connected to the 9 strips of the posterior end of the basal body.The flagellar tail is the conventional ＂9＋2＂ axoneme.