256 INTERNAL SECRETIONS 



formed. After all it seems clear that the hormonic function 

 accomplished by the corpus luteum can be performed also by 

 different kinds of follicles becoming atretic, by epithelioid 

 interstitial cells passing from the latter into the stroma. A 

 similar statement was made by Sand (1919, pp. 141 and 175) 

 as a result of experiments upon ovarian transplantation. As 

 to the hormonic effect, there is no essential difference between 

 the cells of follicles undergoing atresia and the cells in process of 

 being changed into those of corpora lutea. The corpus luteum 

 graviditatis seems to represent merely a new and plentiful 

 supply of very active endocrine cells resembling all the other 

 epithelioid interstitial cells of the ovary. 



We see that the second question we have set ourselves must 

 be answered also in a positive sense. There is evidently a close 

 functional relationship between the interstitial cells and the 

 corpus luteum. We must assume that, as to the hormonic 

 function, they differ from one another only quantitatively. 



There are many other proofs of this contention. It is known 

 that the number of atretic follicles in the human ovary is much 

 increased in pregnancy. All authorities have made similar 

 statements, although they disagree very much as to the 

 interstitial tissue in the ovary; the latter disagreement is 

 evidently due, as already mentioned, rather to a difference 

 in terminology than to conflicting observations. Now it is of 

 great interest to note that, according to Aschner, the increase 

 in follicular atresia in the human ovary takes place in the 

 second half of gravidity, i.e., when the corpus luteum has 

 already undergone degeneration. If this statement of Aschner 

 is true, one might agree with Biedl (p. 337) that evidently the 

 interstitial cells derived from the atretic folhcles take up the 

 function of the lutein cells of the corpus luteum after degenera- 

 tion of the latter; possibly lutein cells of the theca interna take 

 up the function of the lutein cells of the granulosa. A further 

 proof of the above thesis seems to be given by the observation 

 of Aschner that the interstitial tissue is more developed in 

 those species where the number of young in the litter is greater. 

 The view taken by Aschner is worth further comparative 

 investigation. (See the statement of Athias on p. 217.) 



The observations made by Athias (1921) on the motility of 

 the uterus are also a proof that the corpus luteum is not the 

 only organ concerned in hormone-production. Athias stated 



