Studies on the Roles of Androgen, Estrogen and Progestin in the Early Stages of Spermatogenesis

The present study examined the ability of various steroids and hormones to induce in vitro spermatogonial proliferation in cultured testicular fragments of two teleost species. Results indicate that the three steroids 11-ketotestosterone (11-KT), 17 alpha,20 beta-dihydroxy-4-pregnen-3-one (17 alpha,20 beta-DHP) and 17 beta-estradiol (E-2) and salmon pituitary glycoprotein fraction (SPG) were able to induce DNA synthesis, spermatogonial renewal and/or spermatogonial proliferation in Japanese huchen (Hucho perryi), and 100 pg/mL of 17 alpha,20 beta-DHP was sufficient to induce spermatogonial proliferation in the Japanese eel (Anguilla japonica). From these results, we concluded that 11-KT is necessary for the initiation of spemtogenesis; estrogen is necessary for spermatogonial stem cell renewal; and 17 alpha,20 beta-DHP promoted DNA synthesis, and plays a significant role in the proliferation of spermatogonia during mitosis.