Kim Jin Hee, Chung Jae Seung, Lee Ki-Young
Marine Eco-Technology Institute, Busan 608-830, Republic of Korea.
Department of Urology, College of Medicine, Inje University, Busan 614-735, Republic of Korea.
Dev Reprod. 2013 Jun;17(2):121-32. doi: 10.12717/DR.2013.17.2.121.
Ultrastructural characteristics of the germ cells and accessory cells in testis during spermatogenesis and taxonomic values of mature sperm morphology of Ruditapes philippinarum were investigated by the transmission electron microscope and scanning electron microscope observations. The testis is the diffuse organ that consists of branching acini containing developing germ cells and accessory cells associated with spermatogenesis. The morphology of the spermatozoon is of the primitive type and is somewhat different to those of other bivalves. The morphologies of the sperm nucleus type and the acrosome shape of this species have a cylinderical type and a modified cone shape, respectively. As some ultrastructural characteristics of the acrosomal vesicle, the peripheral parts of two basal rings show electron opaque part, while the apex part of the acrosome shows electron lucent part. These characteristics of sperm belong to the family Veneridae in the subclass Heterodonta, unlike a characteristic of the subclass Pteriomorphia showing all part of the acrosome being composed of electron opaque part. In particular, a cylinder-like nucleus of the sperm is curved. The spermatozoon is approximately 48-51 μm in length, including a long acrosome (about 2.40 μm in length), a curved sperm nucleus (about 3.40 μm in length), and a tail flagellum. The axoneme of the sperm tail shows a 9+2 structure.
通过透射电子显微镜和扫描电子显微镜观察，研究了菲律宾蛤仔精子发生过程中生殖细胞和附属细胞的超微结构特征以及成熟精子形态的分类学价值。睾丸是一个弥散性器官，由含有发育中生殖细胞的分支腺泡和与精子发生相关的附属细胞组成。精子形态为原始类型，与其他双壳类动物有所不同。该物种精子核型和顶体形状分别为圆柱形和改良锥形。作为顶体囊泡的一些超微结构特征，两个基环的周边部分显示电子不透明部分，而顶体的顶端部分显示电子透明部分。这些精子特征属于异齿亚纲帘蛤科，不同于翼形亚纲的特征，翼形亚纲顶体的所有部分均由电子不透明部分组成。特别是，精子的圆柱状核是弯曲的。精子长度约为48 - 51μm，包括一个长顶体（约2.40μm长）、一个弯曲的精子核（约3.40μm长）和一条尾鞭毛。精子尾部的轴丝显示9 + 2结构。
