シナホリン投与による養殖ウナギの精巣催熟について

概要

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Premature maturation was brought about in cultivated male Japanese eels by the injection of synahorin and the spermatogenesis of the fish was then studied cytologically. The results obtained were as follows: 1. The eels which were reared in sea water only showed on changes in testicular maturity in the early and late multiplication stages. Fish treated with synahorin, when transferred to sea water, exhibited a marked change in maturity and those injected with 200 or 300 ru synahorin showed marked secondary sex characters. Their testes, which arrived at the spermatocyte stage, after being treated four times with synahorin (each time with 100 ru), showed the appearance of spermatozoa in the lobule lumen, and after the sixth treatment with the hormone, the extrusion of sperm occurred in the fish. The spermatozoa obtained showed high motility in sea water. 2. The morphology of the germ cell during spermatogenesis has been described and it resembles that of Anguilla vulgaris already reported. Based on their histological characteristics, the testicular maturity of the eel has been divided into the following five stages. 1) early multiplication stage, 2) late multiplication stage, 3) spermatocyte stage, 4) sperm formation stage, 5) ripe stage.