Female control of male reproductive function in a Mexican Snake.

Male Thamnophis melanogaster court immediately when exposed to estrogen-treated, attractive females and continue courting for 6 to 8 days. Males exposed to estrogen-treated females will court both intact and ovariectomized females. These males undergo a period of testicular recrudescence, whereas males exposed only to ovariectomized females do no. Sexual attractivity can be induced in female T. melanogaster without estrogen treatment by heavy feeding, which results in significant increases in liver size and activity.