THE OVARIES 23 



an internal secretion. This is questionable, although The follicular 

 there is no doubt that they form an external secretion, e P lthelil 

 namely, the liquor folliculi, which is concerned in the 

 ripening and dehiscence of the follicle with the sub- 

 sequent liberation of the ovum (figs. 1 and 2). 



If, as seems likely, the dehiscence of the follicle and 

 the discharge of the ovum are under the control of 

 another ovarian secretion, the function of the liquor 

 folliculi is a subsidary one and is not of the nature of an 

 internal secretion. Sobotta 1 , Loeb, 2 Novak 3 and others, 

 however, attach importance to the cells of the membrana 

 granulosa as being the forerunners of the cells of the 

 corpus luteum and also of the interstitial cells. I do 

 not believe that such metamorphoses occur in the 

 higher mammals, although I am of the opinion that 

 the cells of the membrana granulosa arise from the 

 stroma-cells of the ovary. It appears to me, as the 

 result of extensive observations, that the interstitial 

 cells and the cells of the corpus luteum arise inde- 

 pendently of the follicular epithelium, as I shall describe 

 directly. 



The corpus luteum. As the Graafian follicle con- The cells of 

 taining the ovum ripens, it is possible to observe an 

 alteration in the cells of the ovarian stroma lying outside 

 the follicular membrane. These cells of the so-called 

 theca interna have become large and polygonal in shape, 

 and are easily to be distinguished from the cells of the 

 membrana granulosa (fig. 3). After dehiscence of the 

 follicle there is great proliferation of the cells of the theca 

 interna to form the corpus luteum. 



The internal secretion of the corpus luteum is believed 

 to have two functions : (1) the regulation of the cyclical 

 changes in the ovaries and uterus in the absence of 

 fertilization of the ovum; (2) a beneficial influence on 



1 Sobotta, J., Archiv. MiTcr, Anat., 1896, vol. xlvii, p. 261 ; Anat. 

 Hetfe, 1897, vol. viii, p. 469. 



2 Loeb, L., Trans. Amer. GynecoL Soc., 1917, voL xlii, p. 172. 



3 Novak, E., Journ. Amer. Med. Assoc., 1916, vol. Ixvii, p. 1285. 



