Studies on the Proper Dose of Estrogen for Induction of Experimental Cryptorchidism and its Histologic Changes in Rat

Hong, Sung Joon; Choi, Seung Kang

Abstract

For the observation of the histological changes at variable time intervals after estrogen-induced cryptorchidism, we administered different doses of depoestradiol cypionate to 1 week old Sprague-Dawley rats and determined the minimum dose at which the cryptorchidism could be induced in all the rats, and observed the histological changes from 5 weeks after birth at which time the testicular descent into the scrotum normally occurs up to 12 weeks of age, the time of complete maturation. The following results were obtained. l. In cases that the doses above O.2mg of depoestradiol cypionate for each rat were administered cryptorchidism was induced in all the rats but not induced below 0.15mg and all the induced cryptorchidism were bilateral. 2. In the rats to which O.2mg of depoestradiol cypionate was administered, the weight of the testis and the diameter of the seminiferous tubules were significantly decreased compared to those in the control group of rats until 12 weeks after birth. Nevertheless, the rate of increase in these rats was similar to that of the control group. 3. The basement membrane of the seminiferous tubules and Sertoli cells showed relatively few changes. But Leydig cells first appeared in 7 weeks after birth in the estrogen administered group while in the control group the cells continuously appeared after 5 weeks after birth. 4. For the spermatogenesis, in the normal control group, the mature sperms can be observed in 7 weeks after birth while in the estrogen administered group, 12 weeks after birth. The results reveal that the minimum dose at which the cryptorchidism could be induced in all 1 week old Sprague-Dawley rat was O.2mg depoestradiol cypionate for each rat. The spermatogenesis and Leydig cell differentiation in the estrogen administered cryptorchidism were delayed by the effect of estrogen. In addition this study indirectly ascertained that the pathogenesis of unilateral cryptorchidism was not just the deficiency of the gonadotropic hormonal stimulation only. And further observations on the estrogen-administered rats after 12 weeks of age will be required to see whether these histological changes are reversible or not.