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KMID : 0894520100140040269
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Development & Reproduction
2010 Volume.14 No. 4 p.269 ~ p.279
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Germ Cell Differentiations during Spermatogenesis and Ultrastructural Characteristics of Mature Sperms in Male Protothaca (Notochione) jedoensis (Bivalvia: Veneridae)
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Kim Jin-Hee
Park Young-Je
Lee Ki-Young
Choi Moon-Sul
Seo Won-Jae
Chung Ee-Yung
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Abstract
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Some characteristics of germ cell differntiations and the function of accessory cells during spermatogenesis, and mature sperm ultrastructure in male Protothaca (N.) jedoensis were investigated by transmission electron microscope observations. The morphology of the spermatozoa of this species has a primitive type and is similar to those of other species in the subclass Heterodonta. Accessory cells, which are connected to adjacent germ cells, are involved in the supplying of the nutrients for germ cell development. The morphologies of the sperm nucleus and the acrosome of this species are the cylindrical type and cap shape, respectively. Spermatozoa are approximately 46～50 ㎛ in length including a long sperm nucleus (about 2.44 ㎛ in length), an acrosome (about 0.45 ㎛ in length), and tail flagellum (about 42～46 ㎛). The axoneme of the sperm tail shows a 9+2 structure. As some characteristics of the acrosomal vesicle structures, the basal and lateral parts of basal rings show electron opaque part (region), while the anterior apex part of the acrosomal vesicle shows electron lucent part (region). These characteristics of the acrosomal vesicle were found in the family Veneridae and other several families in the subclass Heterodonta. These common characteristics of the acrosomal vesicle in the subclass Heterodonta can be used for phylogenetic and systematic analysis as a taxonomic key or a significant tool. The number of mitochondria in the midpiece of the sperm of this species are four, as one of common characteristics appear in most species in the family Veneridae and other families in the subclass Heterodonta. However, exceptionally, only three species in Veneridae of the subclass Heterodonta contain 5 mitochondria. The number of mitochondria in the sperm midpiece can be used for the taxonomic analysis of the family or superfamily levels as a systematic key or an important tool.
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KEYWORD
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Protothaca(Notochione) jedoensis, Spermatogenesis, Sperm ultrastructure, Accessory cell
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