260 



ELEMENTS OF HISTOLOGY. [Chap. xxxn. 



this membrane is a reticulum with generally one big 

 iiucleolus or germinal spot. 



Between these medium-sized follicles and the 

 small follicles of the cortical layer we find all inter- 

 mediate degrees as regards size of the follicle and the 

 ovum, and especially as regards the shape of the cell* 

 of the menibrana granulosa, the intermediate sizes of 



follicles being 

 lined by a gran- 

 ulosa made up 

 of a layer of 

 polyhedral epi- 

 thelial cells. 



347. The 

 deeper Graafian 

 follicles, i.e., 

 those that are 

 to be regarded 

 as big follicles, 

 contain an 

 o v u m o c c a - 

 sionally, two or 

 even three ova 

 which is simi- 

 lar to that of 

 the previous fol- 

 licles, except 

 that it is larger, 

 ;md its zona pel- 

 lucida thicker. The ovum does not fill out the whole 

 cavity of the follicle, since at one side, between it and 

 the membrana granulosa, there is an albuminous fluid, 

 the rudiment of the liquor folliculi. 



348. The largest or most advanced follicles are of 

 great size, easily visible by the naked eye, and con- 

 tain a large quantity of this liquor folliculi (Fig. 143). 

 In fact, the ovum occupies only a small part of the 



Fig. 143. A large Graafiau 'Follicle of the 

 Ovary of Cat. 



The follicle is limited by a capsule, the theca folliculi ; 

 the membrana trranulosa is composed of several 

 layers of epithelial cells. The ovum with its distinct 

 hyaline zona pellucida is embedded in the epithelial 

 cells of the discus proligerus. The cavity of the 

 follicle is filled with fluid, the liquor folliculi. 



