Seasonal changes in testosterone levels and androgen-dependent organs in male moles (Talpa europaea).

Seasonal changes in testicular and plasma testosterone levels and in androgen-dependent organs were determined in moles breeding at 53 degrees N. Although the testes contain up to 30 times more testosterone during spermatogenesis than during sexual quiescence, appreciable quantities of this hormone are present during late summer and early autumn. Annual spermatogenesis lasts for only 2 months, but in some moles spermatozoa remain in the epididymis for up to 3 months after the testes have begun to involute, and may therefore be available to inseminate females coming into a second oestrus.