16G H. TucHMANN-DurLESSis and L. Mercier-Parot 



With regard to the problem of the influence of the maternal 

 pituitary on the development of the embryo, our experiments 

 with hypophysectomy on the 12th day of pregnancy, that is, 

 when the placental secretion is sufficient to make up for the 

 hypophyseal gonadotropins, show that hypophysectomy at 

 this stage is generally well tolerated, and we had only a few 

 postoperative abortions. The progress of pregnancy is in 

 most cases normal. The foetuses removed on the 20th day 

 are normal and their weight identical with that of embryos 

 from control rats which had undergone a spurious operation. 

 The average weight of the offspring of hypophysectomized 

 mothers is 2-12 g. as compared with 2-20 g. for the controls. 

 Our results confirm those of Campbell, Innes and Kosterlitz 

 (1953), and in no case have we observed any diminution in 

 weight like that reported by Knobil and Caton (1953). More- 

 over, when pregnancy is allowed to proceed to term and after, 

 it is observed that foetal growth continues. With the excep- 

 tion of two rats which gave birth on 22nd-23rd day to live 

 foetuses of normal weight, the others showed difficulty in 

 giving birth and we had to have recourse to artificial deliveries 

 between the 24th and 25th day in order to recover the 

 foetuses. It is interesting to note, on this point, that with the 

 prolongation of gestation, the weight of the foetuses increases 

 even in the absence of the pituitary, and that those removed 

 on the 24th day weigh 5 • 6 g. 



Discussion 



These observations show that the development of the 

 embryo is relatively independent of the pituitary control. 

 When one compares the results of our experiments with 

 hormone therapy and hypophysectomy, one is led to con- 

 clusions which are directly opposed to frequently expressed 

 opinions on the part played by somatotrophic hormone in 

 embryonic growth. In point of fact, taking as a basis the 

 experiments with STH administration in course of which 

 foetal gigantism was thought to be observed in the rat, Young 

 (1953) admits that the somatotrophic activity of the pituitary 



