Effect of chorionic gonadotrophin on testicular histology and testosterone production in Tilapia leucosticta (Teleostei: Cichlidae
Kirschner, Marvin A.
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Eight adult male T. leucosticta were given daily injections of 500 IU human chorionic gonadotrophin (Pregnyl, Organon) intraperitoneally for 1 week. These fish showed marked increases in testicular size, gonosomatic index, interstitial cell and nuclear sizes, and spermatogenesis when compared to a similar control group injected with deionized water. The testosterone content of the testes and blood of CG-treated fish rises sharply, and parallelsthe histological parameters. These data indicate that in Tilapia, as in higher vertebrates, iterstitialtissue is stimulated by gonadotrophin to produce testosterone. Interstitial cell activityis a good index of androgen production. (Endocrinology 87: 819, 1970)