338 ELEMENTAEY PHYSIOLOGY. [XXXII. 



cells of the membrana granulosa become cubical 

 or short columnar and the ovum has a membrane, 

 the zona pellucida. 



c. The large Graafian follicles. Note in these 



a. The stroma investment of the follicles, 

 consisting chiefly of spindle-shaped cells, 

 partly of fine fibrous tissue ; inside this 

 is the membrana propria. 



/3. The membrana granulosa, several cells 

 deep, those next the membrana propria 

 being short columnar cells, the rest 

 flattened polyhedral cells. 



7. The central space of the follicle. 



6. The cumulus proligerus projecting 

 into the space ; it consists of a mass of 

 cells much like those of the membrana 

 granulosa and continuous with them, 

 and it encloses 



6. The ovum, like the ovum of the small 

 Graafian follicles but with all its parts 

 larger and its cell-substance (beginning 

 vitellus) more granular; it has further 

 a distinct investing membrane which in 

 some is much thickened so as to form a 

 zona pellucida; from this the cell- 

 substance frequently shrinks in the 

 process of hardening. The cells of the 

 cumulus which lie next the zona pel- 

 lucida are frequently arranged in a 

 radiating manner. 



