Abstract
Newborn male rats were castrated on the day of birth (=day 1) and injected subcutaneously with either 100μg of 5α-dihydrotestosterone (DHT), 500μg of DHT, 50μg of testosterone propionate (TP) or oil vehicle on day 5. At 45days of age, they received subcutaneous ovarian transplantation. At autopsy on day 90, ovarian grafts from the TP group contained numerous large vesicular follicles but no corpora lutea (CL). However, ovarian grafts from DHT-treated and control rats were characterized by the presence of numerous CL and a number of developing follicles. Similar results were obtained in the experiments on female rats. Treatment with DHT on day 5 could not alter the postpubertal ovarian function. All DHT-treated rats showed normal vaginal cycles. They became pregnant when placed with normal males. In contrast, treatment with TP resulted in anovulatory sterility. All rats showed persistent vaginal estrus untill autopsy on day 90. Futhermore, DHT did not prevent this sterilizing action of TP when given in combination with TP. These results suggest that DHT is not normally involved in the differentiation of the masculine type of the hypothalamus in the rat.
