Spermatogenesis in larval Ambystoma tigrinum: Positive and negative interactions of FSH and testosterone

Abstract

Hypophysectomized larval Ambystoma tigrinum were treated for 20 days with either saline, FSH, testosterone, or FSH+testosterone. Larvae from each of these groups were either killed on day 21 or treated for a second 20 days with either saline, FSH, testosterone, or FSH + testosterone. Testes from larvae treated with FSH for 40 days had large germinal cysts, many of which contained primary or secondary spermatocytes. The secondary spermatogonial cysts, which developed following 20 days of FSH-treatment, degenerated during the second 20-day period of experimentation unless FSH-treatment was continued. Depending on the testicular condition, testosterone inhibited or stimulated spermatogenesis. If testes were treated for at least 20 days with FSH + testosterone and did not receive prior testosterone-treatment, testosterone inhibited the FSH-induced proliferation of secondary spermatogonia. Conversely, if FSH+testosterone treatment followed treatment with testosterone, testosterone enhanced the FSH-induced spermatogenesis.