Albino male rats were injected subcutaneously (sc) one month after castration with 1 mg of testosterone (T) or dihydrotestosterone (DHT) daily for two weeks. Every twelve hours a pair of rats were injected iv with tritiated thymidine and killed one hour later. The first pair of rats were killed 7 h after the first hormone injection. The accessory sex organs were weighed and processed for radio-autography.
The weight response of the accessory sex organs was of the same magnitude after T and DHT. However, DHT was slightly more effective in inducing the growth of the seminal vesicle, the coagulating gland, the preputial gland and the epididymis. The organs reached a constant weight in about 8–10 days after the onset of the hormone treatment. The accessory sex organs could be divided into two groups on the basis of their weight response to DHT and T: 1) Highly responsive tissues (seminal vesicle, coagulating gland and prostate) showed a 5–8 fold increase in weight to 1 mg of DHT or T during stimulation over two weeks. 2) Less responsive tissues (epididymis and preputial gland) can only double their weights during the treatment.
By measuring the mitotic response to castration and to the administration of DHT or T the tissues could be categorized into two similar groups:
Seminal vesicle, coagulating gland and prostate are highly dependent on androgen supply, since their mitotic activity increases dramatically in 42–66 h after the initiation of hormone administration. This first DNA
synthetic peak is followed by irregular series of peaks of decreasing amplitude. In six days the fluctuation in the mitotic activity is stabilized to the level of the uncastrated control animals. In addition, these organs respond slightly more rapidly and more extensively to DHT than to T.
The epithelial cells of the preputial gland are less dependent on androgen supply. A significant degree of mitotic activity still persists after castration. The mitotic activity increases 18 h after androgen administration. Fluctuations of mitotic activity are retained during the entire two weeks' period.