Maturatioji of the Graafian Follicle 



45 



face of the ovary and serving to divide the germinal epithelium 

 into a superficial, columnar layer and a deeper one broken up 

 into irregular columns or clumps of spherical or polygonal cells. 

 In these cell masses the permanent ova, developed from the prim- 

 itive ova, become much larger, while the nucleus or germinal 

 vesicle enlarges and its enveloping membrane becomes distinct. 

 The contents of the nucleus become massed at one point and 

 form a distinct reticulum, in which one or more nodal po'ints en- 

 large to constitute the nucleoli or germinal spots. The neighbor- 

 ing germinal cells become arranged about the ovum in a manner 

 to completely enclose it in a follicle, which has at first a single 

 layer of cells. Later a second layer of cells forms about the ovum 

 within the first. 



Fig. 6. Section through part of the ovary of an adult rabbit. 

 The section is taken vertical to the surface of the ovary, and shovps 

 one fully formed Graafian follicle, and others in various stages of 

 development. X 5°- 



GA, Follicle cells surrounding an ovum. 



GB, outer layer of Graafian follicle, or ' ' tunica granulosa. ' ' 



GC, inner layer of Graafian follicle or " discus proligerus." 

 GK, Cavity of Graafian follicle. 



OE, Outer layer of columnar epithelial cells, investing the ovary. 

 OW, Ovum. OY, Primitive Ovum. 



OZ, Nests of Epithelial cells derived from the deeper layers of 

 the genital epithelium. ( Marshall. ) 



