青蚶精子的生殖进化特征

用透射电镜(TEM)研究了青蚶成熟精子的形态结构，分析了其生殖进化特征，成熟精子包括头部和尾部两部分，头部由顶体与细胞核构成，顶体似伞状，覆盖于细胞核前端，轴向纵切面观呈倒的浅V字形，可见有明显的横纹；顶体下腔似乳头状，其内有颗粒状物质分布，细胞核呈圆桶状，前端中央有-U字形核前窝，后端中央有一倒V字形核后窝；核物质高度浓缩，电子密度高而均匀，精子的尾部包括中段和末段，中段由5个(偶见6个)球状或椭球状线粒体围绕中心粒复合体构成；末段细长鞭状，由质膜和轴丝组成，轴丝为典型的“9 2”结构，从精子的超微结构可以追寻蚶科动物的系统演化途径，青蚶精子在蚶科动物生殖进化中占据重要的地位。

Reproductive evolutionary characteristics of spermatozoa in Barbatia virescens

The ultrastructure of mature spermatozoon in Barbatia virescens was observed by using transmission electron microscope and its reproductive evolutionary characteristics was analyzed. The mature spermatozoon consists of a head and a tail. The head is composed of acrosome and nucleus. The acrosome located in the front of nucleus is in the shape of an umbrella. When seen in the axis longitudinal section, the acrosome is upside-down V-shaped, and transverse striations can be seen clearly. The subacrosomal space containing granular materials is nipple-shaped. The nucleus is cylinder in shape, the U-shaped anterior and upside-down V-shaped posterior invagination lie in the centers of its front and back, respectively. The contents in the nucleus are highly dense, and the electron density is homogeneous. The tail of the spermatozoon includes a middle piece and an end piece. Five (or six occasionally) spherical or elliptical mitochondria surrounding the centriole complex make up a middle piece. The slim and whip-alike end piece consists of a plasma membrane and an axoneme which is a typical '9+2' structure. A phylogenetic path can be traced by the study in the ultrastructure of spermatozoa in the Family Arcidae. The spermatozoon of Barbatia virescens has a very important status in the reproductive evolution of the Family Arcidae.