21 G 



XOHMAL HISTOLOGY. 



may serve to explain the fact that the younger Graafian follicles 

 are most abundant in the peripheral portion of the stroma. At 

 first the Graafian follicle consists of a large central cell, the ovum, 



Fig. 193. 



Section from the ovary of an adult bitch. (Waldeyer.) a, germinal epithelium : b, b, columns 

 of germinal epithelium within the stroma; c, c. small follicles; d, much more advanced 

 follicle ; e, discus proligerus and ovum ; /, second ovum in same follicle (a rare occur- 

 rence) ; g, fibrous coat of the follicle: h, basement-membrane; i, membrana granulosa 

 of epithelium; d, liquor folliculi: k, old follicle from which the ovum has been dis- 

 charged (corpus album) ; I, bloodvessels ; m, m, sections of the parovarium ; y, ingrowth 

 from the germinal epithelium ; z, transition from the germinal epithelium to the peri- 

 toneal endothelium. 



surrounded by an envelope of somewhat flattened epithelial cells, 

 which arc in direct contact externally with the unmodified, highly 

 cellular tissue of the stroma (Fig. 194). 



As the Graafian follicle develops, its position in the ovary becomes 

 more central, and the cells around the ovum lose their flattened 

 shape and divide, forming a double layer of cubical or columnar 

 cells. These two layers then become separated by a clear fluid. 



