W HEN A MALE RAT, in the prepubertal period, is treated with testes extract (i) or with testosterone or testosterone propionate (2) the testes are severely damaged: they are reduced in size and weight while spermatogenesis is seriously delayed or completely arrested. When testosterone propionate was ad' ministered to adult rats, no damaging effect was observed. As early as 1932, Moore and his collaborators showed that the damage induced by male sex hormone in young rats resulted from suppression of the pituitary.The experiments here reported were undertaken in order to study the effect of testosterone propionate treatment begun in the prepubertal period and continued beyond maturity, as well as the duration of the post treatment effect. Some observa' tions made in the course of our experiments prompted us to include the investigation of an apparent stimulating effect of testosterone propionate.
MATERIAL AND METHODSThe inbred strain of rats used originated from the Wistar strain and was bred in our own colony for several years. The animals were fed on Purina Dog Chow with the addition of lettuce twice weekly. They were permitted free access to water. Litter'mate controls were used in every experiment. A total of 45 rats was studied. Testosterone propionate 1 was given from the first day of life to all but one series which is specifically mentioned below. Fertility was tested by mating with normal females. If no pregnancy occurred, the fertility of the females was verified by mating with normal males.At the end of the experimental period, the animals were killed and dissected. Organ weights were taken on a torsion balance after dissecting away all connective tissue. Organs were fixed in Zenker formol, imbedded in paraffin, sectioned and stained with hematoxylin eosin. One testis was usually fixed in Susa or Bouin and imbedded in paraffin by the dioxan method, sectioned and stained as above.
RESULTSCroup 1. A. In this group each of 14 rats from 9 litters received 1 mg. of tes' tosterone propionate 3 times weekly for periods varying from 22 to 298 days. They were killed at the end of the experiment. The weights of the testes are given in table 1. The decrease of testes weight over that of the litter'mate controls was well marked after the second month. There was no parallel between the amount of testicular weight loss and either age or total dosage. Histological examination revealed marked