Spermatogenesis and Ultrastructural Characteristics of Spermatozoa of Brackish Water Diploid Clam, Corbicula japonica (Bivalvia: Corbiculidae)

• Published in: Balsaeng'gwa saengsig Vol. 13; no. 2; pp. 115 - 122
• Main Authors: 전제천, 김봉석, 정의영, 김진희, 박갑만, 박성우
• Format: Journal Article
• Language: Korean
• Published: 한국발생생물학회 30.06.2009
• Subjects: Diploid; Spermatogenesis; Corbicula japonica
• ISSN: 2465-9525; 2465-9541

기수산 2배체 일본재첩(Corbicula japonica)의 정자형성과정 및 정자의 미세 구조적 특징을 전자현미경 관찰에 의해 조사하였다. 세포학적 조사 결과, 기수산 2배체인 일본재첩의 정자 길이는 약 55이다. 정자 두부(길이 약 12)는 길게 신장되어 있으며 약간 구부러져 있다. 정핵 길이는 7.90 , 첨체 길이는 약 2.70 이다. 정자의 핵과 첨체의 형태는 각각 긴 화살 모양과 길다란 원추 모양을 나타낸다. 본 종(체외수정, 자웅이체, 난생종 Spermatogenesis and ultrastructural characteristics of sperm of brackish water diploid Corbicula japonica were investigated by electron microscope observations. Based on the cytological studies, the spermatozoon of this species (brackish water diploid) C japonica is approximately 55 in length. The sperm head (about 12 long) is elongated and tapers with a slight curve. Sperm nucleus is about 7.90 long, and the acrosome is about 2.70 long: The morphologies of the sperm nucleus type and the acrosome shape of this species are a long arrow-like type and long cone-like shape, respectively. The sperm head of this species (external fertilization, dioecious and oviparous species) is partially modified from that of the primitive type, as seen in triploid Corbicula species (internal fertilization, hermaphrodite and ovoviparous species), reported by some authors. However, this species produces uniflagellate spermatozoa, unlike freshwater triploid hermaphroditic clams being possessed of partially modified biflagellate spermatozoa. Diploid C japonica is similar to those of other bivalves being possessed of a short midpiece containing four mitochondria surrounding the centrioles. 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, and from uniflagellate sperm cross sectioned, in particular, wing-like axonernal lateral fins are observed, as seen in external fertilization fishes.