Discussion 127 



intra-uterine foetuses died quickly after castration, the abdominal ones 

 survived and grew. Progesterone is necessary only for the intra- 

 uterine development. 



Castration in the pregnant rat does not always stop development of 

 all foetuses. Some may survive, but they are often deformed by uterine 

 pressure. In a series of personal experiments, the weight of such 

 foetuses found alive on day 21 was about 4-4 g., with controls of the 

 same strain of 4 • 9 g. Despite the uterine impairment, foetal growth was 

 not very much reduced by the absence of the corpora lutea. 



Amoroso: Of course, you make the assumption that there is no extra 

 gonadal source of progesterone there. 



Jost: Yes, but in the rabbit and in rats there is not too much pro- 

 gesterone present; at least it has never been detected. 



Amoroso: There is enough, nevertheless, to maintain abdominal preg- 

 nancies in ovariectomized rabbits. Moreover, I believe that both 

 Professor Courrier and Professor Klein would dispute your point. 



Huggett: May I just comment on these two points; first, I entirely 

 agree, I do not think progesterone is necessary for the growth of the 

 foetus ; all that I want to suggest is that it appears to alter the permea- 

 bility and, therefore, nutrients seem to get into the foetus and I take 

 it — I have no knowledge — but I guess that the foetus thus gains a better 

 supply and it can grow a little better. That is as far as one can go. 



T.-Duplessis: Concerning the relationship between the placental 

 weight and the foetal weight, Prof. Huggett quoted an observation of 

 Adair and Thelander. We have also found that when pregnancy is pro- 

 longed in the rat for 3 or 4 days, both the placental and the foetal 

 weights increase. So this raises the question whether the placenta 

 determines the length of pregnancy ? We think that the placenta is able 

 to function for a longer period of time than it normally does; in fact, 

 when we looked at the placenta in pregnancies prolonged for 3 or 4 days 

 they looked quite normal. It seems that ageing is not a definite process 

 of the placenta : the placenta can reach a greater age than it normally 

 does without showing ageing phenomena. 



Huggett: Which function were you studying when you said the 

 function ? 



T.-Duplessis: The foetal-maternal exchange. Since these foetuses 

 are still alive 3 or 4 days after term and are bigger than normal we may 

 assume that the placenta does function correctly. 



Amoroso : A considerable amount of work has been carried out on the 

 prolongation of pregnancy in these animals by Hill and Parkes, and by 

 Professor Wislocki and his associates which antedates the work of 

 Sir Joseph Barcroft. 



Huggett: Yes, and they showed that if the foetus does go on too long, 

 then it asphyxiates itself. 



A?noroso: For my guidance, might I ask Professor Huggett what 

 exactly did he weigh when he worked on the goat's placenta? 



Huggett: The cotyledons, not the membranes. 



Amoroso: You stripped the membranes from the caruncles? 



Huggett: No, we took the caruncles, cut them off leaving the rest of 



