Histological Studies On The Testis Of Tilapia Leucosticta And Other Species Of The Genus Tilapia (pisces: Teleoste)1

Abstract

ABSTRACT: Histological studies carried out on specimens of the cichlid fishes T. leucosticta, T. nigra, and T. zillii collected in the East African Rift Valley crater lake, Lake Naivasha reveal that various stages of sexual maturity are encountered at all times of the year. Spermatogenesis which appears identical in the three species as well as in the West African species, T. macrocephala, is described in detail. A method for estimating the testicular maturity from the mean lobular estimation is proposed par- ticularly for those fishes that are continuous breeders. The interstitial tissue in Tilapia is localized in two places, peripherally and in the typical higher vertebrate interlobular position. The latter appears to have a cycle of proliferation and breakdown reaching a peak at just before the maximum spermatozoan density. There is a close correlation between the activity of the peripheral interstitium and the spermatogenetic activity and it is suggested that the peripheral interstitium exerts a spermatokinetic effect on post-spermatogonial proliferation.