14 Discussion 



Did you observe any inhibition of the Miillerian ducts in explants with 

 the testes? 



Price: I did not mention the Miillerian ducts because of lack of time. 

 Our results on these ducts are still being studied and will be reported 

 soon by Pannabecker. 



We found that explanted Miillerian ducts of both males and females 

 were more difficult to culture at 15 \ and 16^ days than Wolffian ducts. 

 They were actively growing and in a critical period of development 

 at the time of explantation and they tended to become discontinuous 

 under all our culture conditions. As I say, they had rather a hard 

 time but they continued to develop and formed the prostatic utricle in 

 males and the uterovaginal canal in females. 



When we explanted older tracts, the Miillerian ducts of males re- 

 gressed and the Miillerian ducts of females were retained under all 

 experimental conditions. The Miillerian ducts of females were stimu- 

 lated, not inhibited, when foetal testes were placed against them or 

 male hormone was put in the clot. However, I do not think that this 

 indicates that there is no possibility that foetal testis hormone may 

 inhibit the Miillerian ducts of males. 



Jost: Did you see any difference in the prostatic development of 

 tracts which were taken on day 16i and those taken on day 17|? You 

 showed that some prostatic buds appear, but the testis begins to work 

 earlier than day 17£ and by that time the testis has been able to act on 

 the urogenital sinus for about one day. I would also like to draw atten- 

 tion to the fact that in some of these cultures the effect of the distance 

 from the testes was very conspicuous ; I observed some years ago such 

 a spatially restricted activity of the testis in vivo under certain circum- 

 stances, a point which has sometimes been questioned, and I am very 

 glad to see that the same thing occurs in vitro. 



Price: This question brings up the relation of development of pro- 

 static buds to testis hormone. It appears that the testes are already 

 secreting hormone in the foetus between 15| and 16£ days. A few 

 prostatic buds appeared in male tracts explanted at 16^ days without 

 testes, but more numerous buds developed in such tracts explanted at 

 17^ days. This corroborates some of your findings in foetally-castrated 

 male rabbits. I agree that this indicates longer action of testis-secreted 

 hormone on the urogenital sinus. 



I may say that in our cultures prostatic buds developed in explanted 

 female tracts with ovaries present and without ovaries. Most of these 

 tracts were from females of our stock — loosely called a strain — that has 

 had a relatively high frequency of female prostate glands. If we accept 

 the conclusions of Mahoney (1942) and Mahoney and Witschi (1947) 

 that the determination of the female prostate in female prostate strains 

 of rats is genetic and not hormonal, we do not need to assume that 

 androgenic hormone is necessary for the development of all prostatic 

 primordia in the rat. Later Witschi (1948) postulated that the deter- 

 mination is hormonal — foetal ovarian androgen in the female and 

 testicular androgen in the male. 



This may be so but I find it difficult to understand all the variability 



