INTERNAL SECRETION OF OVARY 239 



the precise factors whereby the variation in the ovarian graft 

 according to the sex of the host into which it is transplanted 

 can be explained. 



The above statements in regard to the condition of the 

 ovarian graft have an especial bearing upon the question as 

 to the cells involved in the endocrine functions of the ovary. 

 We have already learned that signs of castration are absent if 

 the implanted ovary " takes." Now Marshall and Jolly stated 

 that signs of castration are absent also, if an atresia of all the 

 follicles has taken place. Bell (1920, p. 47) implanted in the 

 rabbit only the central part of the ovary, which contains no 

 follicles, and is composed entirely of interstitial cells (as 

 shown in serial sections of the graft); twenty-four days 

 afterwards there was no atrophy of the uterus. From all these 

 observations one must conclude that the epithelial and 

 epithelioid interstitial cells of which such a graft is composed 

 are able to perform the internal secretory functions ascribed 

 to the ovary. But the objection may be made that not- 

 withstanding the highly augmented follicular atresia and 

 notwithstanding the transformation of a very great number 

 of follicles into interstitial cells, ova were still present in 

 the grafts, and that these elements might have produced 

 the internal secretion. This is the same objection that we 

 had to deal with before, when discussing in the preceding 

 section the experiments in which a more or less complete 

 atresia of the folHcles was obtained by means of X-rays. 

 Such an objection was made b^^ Bucura (1913, p. 1839). 

 But it was shown experimentally that this objection is 

 not justified, although the fact remains true that ova 

 and young follicles may be present in the transplanted 

 ovary. We have referred to the experiments of Steinach 

 (19 16) where the ovarian grafts were made into castrated 

 males. These grafts were able to feminize the male, in which 

 an hypertrophy of the mammary gland and milk secretion 

 were observed. Steinach's statements were confirmed by 

 Athias (1915, 1916 a, 1916 b), Sand (1918), and Moore (1921 b) 

 and by myself and my co-workers. We must conclude that the 

 great development of the mammary gland was caused by the 

 fact that in the ovarian graft an intensified follicular atresia 

 and an intensified formation of interstitial cells took place. 

 The hypertrophied tissue then gave rise to an increase of 



