전자저널 > 전자저널 > Spermatid Differentiations During Spermiogenesis and Mature Sperm Ultrastructure in Male Crassostrea nipponica (Seki, 1934, Pteroirmorphia: Ostreidae)

Spermatid Differentiations During Spermiogenesis and Mature Sperm Ultrastructure in Male Crassostrea nipponica (Seki, 1934, Pteroirmorphia: Ostreidae)

Jin Hee Kim, Ee-Yung Chung, Ki-Young Lee, Moon Sul Choi, Won-Jae Seo and Sung Han Kim

Korea Ocean & Fisheries Institute, Busan 608-810, Korea Korea Marine Environment & Ecosystem Instittute, Dive Korea, Bucheon 420-857, Korea Department of Marine Biotechnology, Kunsan National University, Gunsan 573-701, Korea Department of Aquaculture

Spermatid differentiations during spermiogenesis and mature sperm ultrastructure in male Crassostrea nipponica were investigated by transmission electron microscope observations. The morphology of the spermatozoon of this species has a primitive type and is similar to those of other bivalves. Mature spermatozoa consist of broad, cap-shaped acrosomal vesicle and an axial rod in subacrosomal materials on an oval nucleus showing deeply invaginated anteriorly, two triplet substructure centrioles surrounded by four spherical mitochondria, and satelite fibres, which appear near the distal centriole. The acrosomal vesicle of spermatozoa of C. nipponica resemble to those of other investigated ostreids. Especially, two transverse bands (stripes) appear at the anterior region of the acrosomal vesicle, unlikely 2-3 transverse bands (stripes) in C. gigas. It is assumed that differences in this acrosomal substructure are associated with the inability of fertilization between the genus Crassostrea and other genus species in Ostreidae. Therefore, we can use sperm morphology in the resolution of taxonomic relationships within the Ostreidea. The sperm is approximately 48-50 μm in length including an oval sperm nucleus (about 1.0 μm in length and 1.41 μm in width), an acrosome (about 0.48 μm in length and 0.30 in width) and tail flagellum (46-48 μm). The axoneme of the sperm tail flagellum consists of nine pairs of microtubules at the periphery and a pair at the center. The axoneme of the sperm tail shows a 9 + 2 structure. These morphological charateristics of acrosomal vesicle belong to the family Ostreidae in the subclass Pteriomorphia.

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