Virilization of Female Rats by Prenatally Administered Progestin1

Abstract

Some of the synthetic progestins administered to pregnant women to prevent spontaneous abortion are known to induce genital virilization in female fetuses. The present study sought to clarify; the virilizing action of one of these progestins, 17[alpha]-19-nortestosterone (Norlutin). Norlutin was administered to pregnant rats for 5 days during the last quarter of gestation. The anogenital distance of the pups was measured at birth. The development of the genitals, ovarian cyclicity and behavioral receptivity were assessed when the animals matured. The degree of genital virilization was found to vary directly with dose of progestin. Females treated with a high dose of progestin never developed an external vaginal opening. Despite pronounced genital virilization, the females did develop ovarian cyclicity and ovulated, and did exhibit the lordosis response which is indicative of sexual receptivity both spontaneously and when given exogenous estrogen and progesterone.