[Comparison of the action of an impeded estrogen, frideron, and of estradiol on the seminal vesicles and on the weight of the testicles and accessory sex glands in the rat. II].

We have undertaken a comparative study on the effects of estradiol and of an impeded estrogen, zeranol, in the prepubescent Wistar male rat. Both had an inhibitory effect on the secretion of F.S.H. in the spermatogenesis test. Nine injections of estradiol or nine ingestions of zeranol had a restraining effect with a dose of 0.5 microgram of estradiol or of 500 micrograms of zeranol (for 100 g of body weight). With some animals, spermatogenesis is interrupted and the weight of the testicles decreased; the treatment is more active with stronger doses: 2 micrograms of estradiol interrupted spermatogenesis in 10 rats out of 11, 1.000 microgram of zeranol interrupted it in 10 rats out of 13. A weak dose of either estrogen (0.05 microgram of estradiol or 20 micrograms of zeranol) stimulated the growth of the seminal vesicles, the prostate gland and the preputial glands. Strong doses decrease the weight of the preputial glands, and even more the weight of the prostate gland (10 micrograms of estradiol, 1.000 microgram of zeranol). They are ineffective on the seminal vesicles. The effects of 2 micrograms of estradiol on the testicles and the accessory sexual glands are completely inhibited by the simultaneous administration of 2 U.I. of P.M.S. rich in FSH.