84 



THE VERTEBRATE OVARY AND ITS RELATIONSHIP TO REPRODUCTION 



been shown that the removal of the ovaries with their corpora lutea invariably 

 results in resorption of the young during the first part of gestation and abortion 

 of the young during the midgestational period, while their removal during 

 the close of gestation permits normal birth to occur (Clausen, '40). The 

 differentiation of the corpus luteum in the snake involves the granulosa cells 

 of the follicle and possibly the theca interna. The differentiated organ appears 

 similar to that of the mammal (Rahn, '39). 



The function of the corpus luteum which develops in the site of the rup- 

 tured follicle in all mammals, including the Prototheria (fig. 49), has been 

 the subject of a long series of studies. (See Brambell, '30, Chap. 9; Corner, 

 '43, Chap. V.) Its function during the reproductive period of the female 

 mammal is described below under the section of the ovarian hormones. 

 The events leading to the formation of the corpus luteum in the mammalian 

 ovary may be described as follows: After the discharge of the egg, the follicle 

 collapses. The opening of the follicle at the ovarian surface through which 

 the egg emerged begins to heal. A slight amount of blood may be deposited 

 within the antrum of the follicle during the ovulation process in some mam- 

 mals. If so, the follicle in this condition is known as the corpus hemorrhagicum. 



BLOO D VE S SELS 



OUTER L AYE R 

 OF THECA 



PROLIFERATING 

 CELLS OF 



Y E R 

 E C A 



LUTEAL CELLS 



VASCULAR 

 SPACE 



MITOCHONDRIA 



CENTRAL CORE 



^ .« '<^ 



1% I .RvC f ^^ 





'Of 



Fig. 49. (A) Luteal cells of the corpus luteum of the opossum. The cellular conditions 

 in other higher mammals are similar. The central core has not yet been invaded and re- 

 sorbed by the phagocytes accompanying the ingrowing luteal cells and blood vessels. This 

 central core is composed of coagulated blood, blood cefls, and connective tissue fibrils. 

 (B) Corpus luteum of the platypus {Ornithorhynchus). 



