868 REPRODUCTION, DEVELOPMENT, GROWTH AND DEATH [CH. UX. 



muscular fibres. It is covered by a layer of cubical cells, called 

 the germinal epithelium, which, in young animals, is seen dipping 



FIG. 555. View of a section of the ovaiy of the cat. 1, Outer covering and free border of the ovary ; I*, 

 attached border ; 2, the ovarian stroma, presenting a fibrous and vascular structure ; 3, granular 

 substance lying external to the fibrous stroma ; 4, blood-vessels ; 5, primary oocytes in their earliest 

 stages occupying a part of the granular layer near the surface ; 6, oocytes which have begun to 

 enlarge and to pass more deeply into the ovary ; 7, oocytes round which the Graafian follicle and 

 tunica granulosa are now formed, and which have passed somewhat deeper into the ovary and are 

 surrounded by the fibrous stroma ; 8, more advanced Graafian follicle with the oocyte imbedded in 

 the layer of cells constituting the proligerous disc ; 9, the most advanced follicle containing the 

 oocyte, etc.; 9', a follicle from which the oocyte has accidentally escaped; 10, corpus luteum. 

 (Schron.) 



down, here and there, into the stroma. The stroma contains a 

 number of yellow polyhedral cells similar to the interstitial cells of 

 the testicle. 



^V^^??-^^5ffifS^2^ 



FIG. 556. Section of the ovary of a cat. A, germinal epithelium ; B, immature Graafian follicle ; C, 

 stroma of ovary ; D, zona pellucida surrounding the primary oocyte; E, Graafian follicle showing 

 lining cells ; F, follicle from which the oocyte has fallen out. (V. D. Harris.) 



Sections of the ovary show that the stroma is crowded with a 

 number of rounded cells, the oocytes, derived from primitive germ 



