Effect of Chorionic Gonadotrophin on Testicular Histology and Testosterone Production inTilapia leucosticta(Teleostei: Cichlidae)

Abstract

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. (Endocrinology87: 819, 1970)