Effect of gonadotropins on the reproductive tract of immature Uromastix hardwicki

Abstract

Morphological changes in the testis, and plasma and testicular androgen levels, during the first 16 weeks of life of the immature spiny-tailed lizard Uromastix hardwicki, have been studied. In the young lizards which emerge from eggs in late June to early July, until approximately three months age , the seminiferous tubules contain only two types of cell: gonocytes and pre-Sertoli cells. Subsequently, in the month of Oc tob e r (age: 13 - 16 weeks) there is a marked proliferat i on of germs cells accompanied by increase in the diameter of the seminiferous tubules and weight of the testis. The interstitial cells which are markedly differentiatiated even in the earliest phase of post-hatching development, ~re considerably hypertrophied in early August (age: 4-5 weeks) . Plasma titers of testosterone, as measured by radioimmunoassay, showed an initial rise in August followed by a second major peak at the end of October. Testicular testosterone concentrations expressed per 100 mg of tissue were lowest in July nd maxima l in Augu st . A significant increase in 2 testosterone concentration both in the plasma and the testicular tissue were observed following administration of FSH and LH to immature animals. The rise in androgen levels in the FSH treated animals was significantly higher than that observed in the LH treated animals. It has been concluded that, in the immature spiny-tailed lizard, steroidogenic activity of the testis precedes gametogenic activity and that, the steroidogenic tissue of the testis in the species is responsive to exogenous gonadotropins even in the earliest phase of post-hatching development .