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Studies on Sharks―IV Testes and Spermatogeneses in Selachians

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Title: Studies on Sharks―IV Testes and Spermatogeneses in Selachians
Other Titles: サメ類に関する研究-4 : サメ類の精巣と精子形成について
Authors: Chen, Che-Tsung / Teshima, Kazuyuki / Mizue, Kazuhiro
Authors (alternative): 陳, 哲聡 / 手島, 和之 / 水江, 一弘
Issue Date: Aug-1973
Publisher: 長崎大学水産学部
Citation: 長崎大学水産学部研究報告, v.35, pp.53-65; 1973
Abstract: The male reproductive organs and the development of sperm cells in the selachians were studied. The reproductive organs of selachians are quite different from those of the teleosts; the testes and ovaries are formed at the anterior ends of epigonal organs which are developed in both sexes, and in male, the testis is connected to the epididymis. The spermiduct extending from the epididymis lies in the kidney, and the posterior end of spermiduct is expanded to form the sperm sac in some species. The spermatogenesis is also different from that of the teleosts, and the cyst is not formed. Moreover, the spermium shows a remarkably different shape in comparison with that of the teleosts; it has a slender and spiral head like a fiber, and many spermiums get together to form a sperm clump. In the seminiferous tubule, the spermiums in the sperm clumps are situated with their heads pointing towards the basement membrane, and with their tail towards the lumen.!?1.The male reproductive organs and spermatogeneses in Galeorhinus japonicus, Mustelus manazo, Carcharhinus dussumieri, C. sp., Rhinobatos schlegeli, Squalus brevirostris, Heterodontus zebra, Heptranchias perlo and Cephaloscyllium umbratile were studied. 2. In these species, a pair of epigonal organs are found, and at the anterior ends of these organs, testes in male or ovaries in female are formed. 3. The testes on selachians consist of seminiferous tubules. In early stage of development, the internal surface of the seminiferous tubule is lined by the seminiferous epithelium. The spermatogonia developed from the basement membrane appear between the seminiferous epithelium and the basement membrane, and the spermatogonia continue to be divided and reduced in size. This is the multiplying period of sperm cells. 4. After the multiplying period, the spermatocytes develop into spermatids by the reduction division, and the tails are formed. At the same time, cell nuclei become slender to form the heads. This is the developing period of the sperm cells. 5. The spermiums of selachians show a special shape and their shape is the same in every species. The head is slender as a fiber and spiral, and the tail is also slender. Approximately 30 spermiums get together to form a sperm clump, and the spermiums in the clump are arranged with their heads pointing towards the basement membrane and with their tails towards the center of lumen. 6. The sperm clumps are sent to the epididymis from the testis, and here, they are dissolved into the seminal fluid by the secreted fluid. 7. The spermiduct runs along the ventral side of kidney, and the internal part is divided into many branches. The spermiduct is quite winding, especially in the anterior half portion of kidney. 8. In Galeorhinus japonicus and Mustelus manazo, the posterior end of spermiduct is greatly modified to form a sperm sac. In other species, the sper-miducts are modified to some extent.
URI: http://hdl.handle.net/10069/30884
ISSN: 05471427
Type: Departmental Bulletin Paper
Text Version: publisher
Appears in Collections:第35号

Citable URI : http://hdl.handle.net/10069/30884

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