INTERNAL SECRETION OF OVARY 227 



According to Goormaghtigh (1921), the interstitial cells of the 

 ovary and of the testicle are formed from the mesothelium like 

 the cortical substance of the adrenals. Being of epithelial 

 origin, these cells are transformed into connective tissue cells, 

 to become later, at the time of sexual activity, epithelioid. 

 Bell (1920) pp. 27, 28) inclines to the view that interstitial 

 cells can be formed even from corpora lutea. 



So we see that the origin of the cells of the interstitial tissue 

 of the ovary may be a very manifold one; the cells of the 

 stroma, the cells of the theca interna, the cells of the granulosa 

 and possibly the cells of the corpus luteum may take part. 

 We are now, indeed, far from the original point of view of 

 Limon (1901) and of Sainmont (1906), who assumed that the 

 interstitial cells originate exclusively from connective tissue. 

 When speaking about "interstitial tissue" or "interstitial cells,'* 

 we always understand c£lls derived from follicles without presum- 

 ing whether they originate from connective tissue or from epithelial 

 cells. In general there seems to be, indeed, great difficulty in 

 •stating in terms of histology what the origin of the cells of the 

 atretic follicle or of the interstitial tissue has been, since so 

 many contradictory statements are to be found. 



An increase of the interstitial cells in the above-mentioned 

 sense as observed during gravidity can be obtained also experi- 

 mentally by the application of the X-rays or by transplantation. 

 Now the question arises whether such an hypertrophy of the 

 interstitial tissue in the ovarian stroma causes an increased 

 endocrine activity on the part of the ovary. It seems clear 

 that the answer to this question might furnish important 

 knowledge as to the function of the interstitial cells. 



3. The Influence of X-rays on the Ovary. 



The statements made by different authors on the reaction 

 of the ovary to X-rays are very contradictory. According to 

 some authors, the follicles and the interstitial cfeUs (or cells of 

 the stroma) are injured by X-rays; according to others, there 

 is only a degeneration of follicles, whereas the interstitial cells 

 may even increase in number. But it seems that in discussing 

 this question it is not always borne in mind that the ovary may 

 react in a different manner according to the mode of irra- 

 diation, according to the species, and to the age and condition 

 -of the animal. As Lacassagne (1913, p. 41) points out, the 



