ANATOMY ASD HISTOLOGY OF THE OVARIES 539 



ments. According to Wallart ('07), they reach their highest development 

 before puberty, but persist throughout sexual life, increasing during preg- 

 nancy.. We know that there is also a considerable development of inter- 

 stitial cells from the thecaB of atretic follicles, which greatly confuses the 

 picture, because the theca interna also furnishes true lutein cells, so that 

 a distinction between interstitial cells and lutein cells is difficult to make 

 and of uncertain value. 



According to Anna Schaeffer ('11), the interstitial cells in the rabbit 

 may be identified by the recations of their fatty droplets as follows: 



Interstitial Cells Lutein Cells 



Sudan III Bright red Orange 



Ponceau Brownish Dark red 



Indophenol Bluish red Deep blue 



Nile blue Stain lightly Stain intensely 



Mulon ( 7 12) has found that the double refraction of the fatty droplets 

 is more marked in the young interstitial cells developing from the thecse 

 than in the lutein cells and in those of the interstitial gland proper. 



Athias (e) ('10, p. 151) claims that the fatty inclusions in the inter- 

 stitial cells are more soluble than those in the corpus luteum. 



Owing to the difficulty of devising a satisfactory method for the 

 enumeration of the interstitial cells, the statistical methods, which have 

 been used successfully in the investigation of other endocrin organs, 

 have not yet been applied. Neither has the growth energy of the cells been 

 measured by the inanition method. We are much in need of information 

 along these lines. 



Comparative Distribution 



The occurrence of ovarian interstitial cells in the vertebrate scale has 

 been by no means satisfactorily determined. It is evident, however, that 

 they are quite as variable as those of the testis. The variations suggest, 

 either that we are wrong in ascribing great functional significance to them, 

 or else that, when they are reduced, the discrepancy is made up by the 

 increased development of some other mechanism. Here, also, quantitative 

 studies are needed. Investigators have not hesitated to group the inter- 

 stitial cells of the ovary and testis, the lutein cells, and the cortical cells 

 of the suprarenal together, because they all contain closely related, some 

 say identical, lipoids. The logical step is to determine whether there is 

 any compensation, that is to say, whether they vary in unison or inde- 

 pendently. It would be interesting also to discover how general is the 

 correspondence between males and females of the same species with respect 

 to the presence or absence of interstitial cells in the gonads. Most of the 

 generalizations which have been advanced thus far are based upon in- 

 sufficient evidence. 



