The effect of males on the reproductive state of female Microtus ochrogaster.

Abstract

Females of a laboratory colony of M. ochrogaster were isolated for ten days and then exposed to males. The responses of the females were measured on the basis of histological changes in the vaginal and uterine epithelia, changes in vaginal smear patterns, and uterine weight/body weight ratios. Exposure to males for 72 hr was maximally effective in inducing estrus. There was little correlation between changes in vaginal smear patterns and in uterine epithelial types or between changes in uterine and in vaginal epithelial types. Castrated females injected with estradiol cyclopentylpropionate (ECP) showed a high frequency of mucification of the vaginal epithelia at a dose level of 0.5 µg ECP, but cornification occurred more frequently than mucification at a dose level of 1.0 µg ECP. Changes in vaginal epithelia were the most sensitive assay of female responsiveness to males or to estrogen injections.