玫瑰无须鲃精子的超微结构

摘要

Transmission and scanning electron microscopy revealed that the spermatozoon of the rosy barb Puntius conchonius consists of an acrosome-less ovoid head,a midpiece and a flagellum.The head mainly consists of the nucleus.There is only a thin layer of cytoplasm between the plasmalemma and the nucleus.The nucleus contains dense chromatin.At the caudal-lateral end of the nucleus there is a shallow nuclear fossa,which partly holds the centriolar complex.The centriolar complex consists of the proximal and distal centrioles,arranged at an obtuse angle with the flagellum linked to the end of the distal centriole.The midpiece is composed of the anterior chief segment,the collar,containing several irregular mitochondria embedded in the cytoplasmic mass,and a slender caudal segment of variable length,the sleeve,behind the collar.The midpiece is separated from the anterior segment of the flagellum by a plasmic channel.Both the head and the midpiece are in asymmetrical emplacement to the position of the flagellum.The flagellum possesses a conventional 9+2 axoneme with no lateral fin.Compared to the structures of other Cyprinidae fish spermatozoa,the main characteristics of this spermatozoon are the variable length of the sleeve,the different vesicles and various pores of the collar.It seems that the number of vesicles and the sleeve length is correlated,this may have some relationship with sperm aging%透射和扫描电镜研究显示玫瑰无须鲃(Puntius conchonius)的精子由头、中片和尾三部分组成.头部无顶体,呈球形或卵圆形,主要由细胞核组成,核内染色质致密.核前端几乎无细胞质存在,核膜紧密靠近细胞质膜,而在核的后端有少量细胞质存在.在核后端偏于一侧处有一个浅的核后凹,中心粒复合体部分地镶嵌于其中,中心粒复合体由近端中心粒和远端中心粒组成,二者呈钝角形排列,鞭毛从远端中心粒的末端发出.中片由前边的主要部分--领和后边细薄的袖套构成.领内含有数个不规则分布的线粒体包埋于细胞质中,袖套的长短、粗细差别较大,有的精子没有袖套.由于与鞭毛的不对称连接,使得头部及中片均呈不对称型.尾是一根细长的鞭毛,尾丝具有典型的"9+2"微管结构,尾部两侧均无侧鳍.与鲤科其它鱼精子相比,该鱼精子的主要特征是具有长短不一的袖套,领内有不同数量的液泡,且有些空泡向外界开口呈孔状.袖套的长短与领内液泡化水平似有某种相互联系,这也许与精子的老化程度有关