516 



THE REPRODUCTIVE SYSTEM 



a layer of follicular epithelium several cells deep. This may be desig- 

 nated the mantle-layer. 



The rapid multiplication of the epithelial cells is soon followed by 

 active secretion, resulting in the formation of a clear fluid by which 

 the cells are more and more separated, and the cytoplasm of adjacent 



FIG. 455. A NEARLY RIPE GRAAFIAN FOLLICLE FROM THE OVARY OF A DOG. 



a, fibrous, and b, cellular layer of the theca folliculi; c, membrana propria; d, mem- 

 brana granulosa, which, as a result of contraction during hardening, has retracted 

 from the membrana propria, leaving a broad artificial space; E, liquor folliculi; 

 /", discus proligerus; g, zona pellucida; /;, vitelline membrane; i, vitellus; k, the ger- 

 minal spot, lying within the germinal vesicle. Hematein and eosin. Photo. X 150. 



cells is then readily seen to be firmly joined together by numerous deli- 

 cate processes which may be regarded as intercellular bridges. Similar 

 processes unite the neighboring cells to the zona pellucida which has 

 already formed about the ovum. 



The accumulation of the fluid liquor folliculi within the follicle soon 

 appears to tear apart certain of the epithelial cells, and a fluid-filled space. 



