ANATOMY OF THE FEMALE OKGANS OF GENEEATION 



79 



follicle consists of a spherical cell, the ovum, closely invested by a single 

 layer of epithelium; these may be seen forming an almost continuous layer 

 near the surface of the ovary. In the deeper parts of the gland, that is to 

 say nearer the hilum, the more developed and larger follicles will be noticed. 



K 



Fig. 232. The Ovary 



A, Peritoneal Coat. B, D, E, P, Cortical Vesicles, c, Blood-vessels. G, Graafian Follicle. H, Stroma. 

 I, Graafian Follicle. J, Germinal Spot. K, Germinal Vesicle. L, Attached border. 



The fully developed or ripe follicles (size about -g inch) are sur- 

 rounded by a fibrous wall, the " tunica fibrosa ", containing a capillary 

 plexus. This is lined by several layers of epithelium, " tunica granu- 

 losa", which in one part is 

 elevated into a little mound, 

 "discus proligerus", in which 

 the ovum is embedded; the 

 rest of the cavity, by far the 

 greater part, is filled with an 

 albuminous fluid, " liquor folli- 

 culi". Pathological cysts are 

 frequently seen in the ovaries, 

 especially of cows and mares, 

 varying in size from small 

 marbles to oranges. These arise in the corpora lutea, and are not to 

 be mistaken for the Graafian follicles. 



The Ovum. This is a spherical cell, just visible to the naked eye 

 (about y^- - inch), composed of the following parts: A transparent 

 finely striated outer investment, the " zona pellucida "; within this is the 

 "vitellus", or "yolk", made up of albuminous and fatty granules consti- 



Fig. 233. The Ovum 



1, Ovum ruptured. 2, Entire ovum. A, Zona Pellucida. 

 B, Space left by retraction of Yolk, c, Vitellus or Yolk. 

 D, Germinal Vesicle. E, Germinal Spot. 



