THE FEMALE REPEODUCTIVE ORGANS 517 



the atitrum follicuU, is thus formed. Such a follicle is known as a vesicu- 

 lar OT_Graafian follicle. Follicles intermediate between the primary folli- 

 cles with a single or double layer of mantle cells and vesicular follicles 

 may for convenience be called intermediate or growing follicles. The 

 epithelial cells are separated by the antrum into two layers: the one, 



FIG. 456. PHOTOMICROGRAPH OF A SECTION OF CAT'S OVARY, SHOWING Two PRI- 

 MARY FOLLICLES AND ONE VESICULAR FOLLICLE. 



adherent to the membrana propria of the follicle, is known as the mem- 

 brana or stratum granulosum; the other, adherent to the zona pellucida 

 of the ovum, is designated the discus proligerus. The two layers remain 

 in contact at one point, and as the liquor folliculi increases in volume, 

 the attached discus proligerus with its contained ovum comes to occupy 

 a more and more eccentric position, and the cells of the stratum granulo- 

 sum, where the two layers are in contact, appear to pile up about the 



