62 B. F. KINGSBUEY 



be expected that in an organ as complicated as the ovary other 

 modes of origin had been advanced. Hence we find the strands 

 of interstitial cells interpreted as degenerating egg-tubes of Pfitiger 

 (Schulin '81} or derived from the Wolffian body (Balfour 78, 

 Harz '84). From the medullary cords of the ovary in the fetal, 

 new-born or young animal the strands of interstitial cells were 

 not readily distinguished and the two structures were confused, 

 notably by Balfour. Genetic relationship to the blood vessels 

 was advanced by His and Mihalkovics. Tourneux and Jan- 

 osik regarded them as connective tissue cells. Miss Lane-Clay- 

 pon ('05) has more recently derived them from the germinal 

 epithelium as cell cords with the potentiality of primordial ova. 

 The appearance of the interstitial cells and their epitheloid ar- 

 rangement led a number to assume an epithelial origin for them. 

 Finally, their resemblance to the cells of the suprarenal organ 

 (cortex) had been commented on as suggestive by Mihalkovics, 

 Janosik, Limon, MacLeod, Van Beneden and Tourneux. It 

 should be noted that while it is quite clear from the literature 

 alone that the interstitial cells of the mature or maturing ovary 

 come from the internal layer of the theca of degenerating fol- 

 licles, those in the fetal or postpartum ovary can have no such 

 origin. This will be discussed subsequently. 



The relation of the problem of the interstitial cells to that of 

 the corpus luteum is to be found in the view that has l^een 

 more or less definitely expressed by many workers — that no 

 fundamental difference exists between the regressive changes 

 that occur in the ruptured and in the unruptured follicle when 

 they undergo degeneration. First definitely expressed, as far as 

 the writer knows by Schulin ('81) who believed he could find 

 intermediate forms between the typical atresia and corpus lute- 

 um formation, the fundamental similarity of the two processes 

 has been insisted on by Paladino ('88), Schottliinder ('91), Hoelzl 

 ('93), Kolliker ('98), Clark ('98), Bouin ('02), Allen ('04), Van 

 der Stricht ('02), Limon ('02), Fellner ('09) and others. The 

 atresia foUiculi has been designated as a corpus luteum atreticum 

 (Kolliker, Van der Stricht), false corpus luteum (Schottlander 

 and others), while by Fellner the interstitial cells are called 



