THE OVA AND OVAllY IN MAN AND OTHER MAMMALIA. 215 



plasm or yelk round the germinal vesicle, even after the latter 

 has reached a definite size. 



The chief function of the membrana granulosa is to 

 nourish the ovum during its development. From the first 

 appearance of the ovum as an ordinary germ epithelial cor- 

 puscle, until the development of the embryo and its 

 extrusion from the uterus, it exists as a parasite. On the 

 surface of the ovary at first it is an ordinary germ epithelial 

 corpuscle. In the ovary, during a certain stage of its 

 development, it is simply surrounded by vascular nutritious 

 tissue, of which, however, it forms no part, but is simply 

 resting on it. Here it imbibes nourishment until it is 

 thrown off from the ovary. It then passes into the ute- 

 rus, where changes due to impregnation occur in it, and 

 processes of its surface become imbedded in the vascular 

 mucus membrane of the uterus, and by the agency of these 

 nourishment is absorbed for the germ till it reaches a certain 

 stage of development, when it is thrown off from the parent. 

 In the uterus, as in the ovary, the ovum is simply sur- 

 rounded by vascular nutritious tissue of which it forms no 

 part, but simply rests on it, and absorbs nourishment from 

 it for its own development. 



In the old follicles, some of the cells of the membrana 

 granulosa show a distinct but fine cell wall round the proto- 

 plasm which invests the nucleus. In some of my prepara- 

 tions of the rabbit's ovary, the division of the nuclei of the 

 corpuscles in the membrana granulosa is excellently seen 

 (fig. 13, v). In these older follicles the protoplasm round 

 the nucleus of the membrana granulosa corpuscle is some- 

 times very extensive, forming a thick layer which may be 

 found drawn out in a fusiform manner (fig. 20, u) at one or 

 more points. 



In certain parts of the adult cat's and rabbit's ovary, we 

 find large patches of granular cells, and running in between 

 the cells are processes of connective tissue. These large 

 granular cells have nuclei, but they are indistinctly seen 

 because of the granular nature of the substance which 

 surrounds them. In most cases the nuclei appear as round 

 or oval bodies with nucleoli. An examination of the patches 

 shows that the granular cells are swollen up individuals of 

 the membrana granulosa from old and probably ruptured 

 follicles, and are undergoing a fatty degeneration, while at 

 the same time connective tissue corpuscles from the wall of 

 the follicle are growing in between them. In almost every 

 old ovary we find large yellow patches, consisting of the cells 

 we have now described. 



