278 PRACTICAL HISTOLOGY [XXXV 



The membrana granulosa, several cells deep, those 

 next the membrana propria being short columnar cells, 

 the rest flattened polyhedral cells. 



The central space of the follicle. 



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 



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 pellucida are frequently arranged in a 

 radiating manner. 



Probably most of the stages between the smallest 

 and the largest follicles will be seen in the specimen. 



d. Large polyhedral cells in the stroma, something 

 like those that occur in the interstitial tissue of the 

 testis. (These are much less numerous in the ovary 

 of the rabbit.) 



In some of the sections taken near the hilus there may be seen 

 lying in the stroma groups of tubules, lined with a short cubical or 

 flattened epithelium, and cut at various angles. These are the tubules 

 of the parovarium. 



3. Take the fresh ovary of a mammal (preferably a 

 large one) ; observe the bulgings due to the more or less 

 ripe Graafian follicles. Holding the ovary on a glass 

 slide, carefully prick the most prominent follicle and 

 receive the contents on the slide. Examine without a 



