A karyometric and stereologic study of the effects of gonadotrophin and testosterone on the interstitial gland of the testis of intact and endoxan treated rats.

Adult male rats were treated daily for 18 days with endoxan in doses of 4 mg/kg of body weight or testosterone in doses 2.5 mg per rat. For the last 5 days of the experiment some of the rats received gonadotrophin injections in doses of 50 I.U. Karyometric and stereologic studies were undertaken on paraffin sections of the testes stained with haematoxylin and eosin. Endoxan treatment decrease the nuclear volume of the Leydig cells and lowers the volume fraction occupied by the interstitial gland in the testis. These changes were accompanied by a decrease in the intensity of reaction for acid phosphatase, non-specific esterases and 3-beta-hydroxy-steroid dehydrogenase. Testosterone injected alone or jointly with endoxan resulted in more pronounced changes than following treatment with endoxan alone. As expected, gonadotrophin injections into intact rats resulted in a marked increase in nuclear volume of the Leydig cells and in the volume fraction of the interstitial gland. This effect of gonadotrophin on the interstitial gland of the rat testis was partially inhibited by endoxan treatment. It follows from these experiments that endoxan impairs the functional activity of the interstitial gland of the rat testes by lowering the endogenous gonadotrophin levels, as well as by direct action on the Leydig cells.