80 BENJAMIN H. WILLIER 



with similar processes attached to other nuclei to form the net- 

 work of the stroma. In this loose network are the interstitial 

 cells, which, in the different gonads of this group vary greatly 

 as to size, shape, and structure. In gonad H-18 they are rela- 

 tively few in number, and possess large, round nuclei and a 

 homogeneous cytoplasm containing a few fuchsinophllic granules. 

 In gonads 42 and 66 the interstitial cells are difficult to recog- 

 nize, owing to the presence of large masses of cells which at 

 ruptured places in the walls of the sexual cords are continuous 

 with the supporting epithelial cells of the sexual cords. The 

 cells within the cords are identical in shape and structure with 

 the cells of these masses. It is not at all improbable that some 

 of these masses of cells lose their specificity as supporting epi- 

 thelial cells and become interstitial cells as a similar process 

 occurs in degenerating follicles of the ovary of a normal mature 

 foetus, where the granulosa cells transform into masses of cells 

 which resemble interstitial cells. 



Two clearly different degrees in the organization of the sup- 

 porting epithelial cells may be recognized. They are either 

 arranged in definite cords or they occur in unorganized masses of 

 cells. The latter are particularly abundant and distinct in the 

 gonad of case 66, less abundant in case 42, and least in H-18. 

 The close resemblance of these cells to the supporting epithelial 

 cells within the sexual cords and their close association with the 

 sexual cords suggest their origin from the latter. Similar masses 

 of unorganized supporting epithelial cells, in addition to the 

 medullary cords, occur in the normal ovary (N 15, 18 cm.). 

 Whether or not these unorganized masses in the free-martin 

 gonads transform into sexual cords cannot be determined from 

 the data at hand, but it is suggested that they do, since these 

 masses are most numerous and largest in the youngest gonad 

 (case 66). Obviously, there is a tendency for these unorganized 

 masses to disappear with increasing age. However, differentia- 

 tion is not entirely the result of aging, but is dependent also on 

 the variability in the action oif the sex hormones. For example, 

 in the gonads of the oldest free-martin examined, the differentia- 

 tion of the sex-cord region is much less than in these younger 

 gonads. 



