GRAAFIAN FOLLICLES 



33 1 



thickened, and in this thickened portion is imbedded the 

 ovum, The epithelial cells of the membrana completely sur- 

 round the ovum, constituting the discus proligerus. The 



FIG. 94. Section of the ovary of a cat, showing the origin and devel- 

 opment of Graafian follicles. (From Yeo after C'adiat.) 



a, germ epithelium; b, Graafian follicle partly developed; c, earliest form of 

 Graafian follicle; d, well-developed Graafian follicle; e, ovum; f, vitelline mem- 

 brane; g, veins; h, i., small vessels cut across. 



cells of the discus next the ovum have their long axes at 

 right angles to the circumference of the egg, and this layer 



