Discussion 173 



DISCUSSION 



Jost: The two kinds of experiments which were shown seem to be 

 rather different. In the first one, pituitary extracts were used and the 

 question immediately arises whether the extracts were completely free 

 of substances stimulating other endocrine glands, such as the adrenals 

 or the ovary. It is well known that maternal hormonal imbalances may 

 interfere with foetal growth. 



Concerning the direct action of growth hormone on the foetus I ob- 

 served no increase in size of rabbit foetuses which were given directly 

 1*5 mg. growth hormone (Choay) under the skin. On the other hand, 

 I observed a considerable reduction of the foetal growth as a result of 

 some maternal hormonal treatments. For instance, I compared the 

 average size of rat foetuses after administration of androgenic com- 

 pounds to the mother. In our colony the mean weight of control foetuses 

 on day 21 is about 5 g. In rats injected with testosterone phenyl- 

 propionate, testosterone oenanthate or androstenediol dipropionate 

 (10 mg./day) from day 15 to day 20 the average weight of the foetuses 

 was about 3 g. ; on the contrary, with methylandrostenediol dipropionate 

 the weight was normal. The exact point of attack of these substances 

 is unknown. I wished to use such examples just to draw attention to 

 the fact that maternal hormonal imbalances may alter foetal growth, 

 and to raise the question of the extent to which the injected growth 

 hormone changed the maternal hormonal equilibrium. 



T.-Duplessis: As far as growth hormone is concerned, I do not think 

 at all that it would be a direct action, as there is good reason to think 

 that such a high molecular weight hormone will never cross the placental 

 barrier. The problem we were studying was the following one: will 

 growth hormone induce foetal gigantism or not ? In the last few months 

 it has been claimed that growth hormone induced foetal gigantism, but 

 we could show that it does not, and we believe that the greater weight 

 of these foetuses is only due to a prolonged pregnancy. How growth 

 hormone prolongs pregnancy, we do not know. It was a very fascinating 

 explanation to say that growth hormone contains some gonadotrophin 

 and, therefore, it will modify the functioning of the ovary. But curiously 

 enough, the results you get with pure growth hormone, that biochemists 

 claim to be devoid of gondadotrophins, are the same as those one gets 

 with crude growth hormone in which there is the high quantity of 

 gonadotrophic hormone. And I may mention also that Prof. Nixon, 

 who utilized a pure growth hormone from a tested Holland preparation, 

 got larger foetuses in the rat. 



I was puzzled by this problem of growth hormone for other reasons 

 because many years ago it was shown that there was a very good corre- 

 lation between the cytological picture of the pituitary and growth, first 

 in the mother. But surely during the pregnancy, there is a big increase 

 of the eosinophil cells which are supposed to be the source of growth 

 hormone. And then other people have shown that in the embryo first of all 

 eosinophil cells appear and they correlate this very early appearance of 

 eosinophils with the function of the somatic development, while the baso- 

 philic cells will directly determine the sexual development of the embryo. 



