| Abstract: | A single injection of 50 microgram testosterone was given to fetal rats on day 17, 18, 19 or 20 of gestation. On day 21, the fetuses were removed from the mother under maternal ether anesthesia, and the length of the urovaginal septum was measured microscopically in female fetuses in order to assess the virilizing effect of testosterone. In fetuses treated with testosterone on day 17, the length of the urovaginal septum was comparable to that of oil-treated littermate controls. In fetuses treated on day 18, the length was significantly abridged compared with controls. In fetuses treated on day 19, the abridgment of the urovaginal septum was most marked. In fetuses treated on day 20, the length of the septum was again comparable to that of controls. The observations suggest that day 19 is the critical day for the virilizing effect of testosterone. Various amounts of testosterone and its metabolites including dihydrotestosterone, androstane-3 beta, 17beta-diol and androstane-3 alpha, 17beta-diol were injected into 19-day-old female fetuses, in order to test the dose relation to the virilizing effects of these steroids in terms of abridgment of the urovaginal septum. As a consequence, it was found that testosterone was the most effective for virilization. |
