17beta-estradiol stimulates proliferation of spermatogonia in experimental cryptorchid mice.

AIM To investigate whether estrogen stimulates the proliferation of spermatogonia or induces spermatogenesis in cryptorchid mice. METHODS Mice were surgically rendered cryptorchid, then treated with different doses of 17beta-estradiol (E2) s.c. once a day. Mice were killed at sexual maturity (45 days of age), and histological analysis and immunofluorescence were performed. Serum follicle stimulating hormone (FSH), estradiol, testosterone and luteinizing hormone (LH) were measured. RESULTS Low doses of E2 had no notable effect on spermatogonia, but at higher doses, E2 stimulated the proliferation of spermatogonia. CONCLUSION E2 has a dose-related mitogenic effect on spermatogonia.