862 GENERATION. 



the smallest ova, a little more than J^TT of an inch. The primordial ova have the form 

 of rounded cells, each with a large, clear nucleus, and a nucleolus. Other structures are 

 developed in and surrounding these cells, as they arrive at their full development. 



The most interesting stage in the development of the ova and Graafian follicles is 

 observed at about the period of puberty. At this time, a number of follicles (twelve, 

 twenty, thirty, or even more) enlarge, so that we have all sizes, between the smallest 

 primordial follicles, -^ of an inch, and the largest, nearly an inch in diameter. In 

 follicles that have attained any considerable size, we have the fully-developed ova, one in 

 each follicle, except in very rare instances, when there are two, and these ova have a 

 pretty uniform diameter of about y^y of an inch. In the process which culminates in 

 the discharge of the ovum into the fiinbriated extremity of the Fallopian tube, the Graa- 

 fian follicle gradually enlarges, becomes distended with liquid, and finally breaks through 

 and ruptures upon the surface of the ovary. It becomes necessary, then, to study the 

 structure of these large follicles and their relations to the ova ; but, before we do this, 

 we can review, with advantage, the relations of the different portions of the ovary and 

 the follicles and ova of various sizes, by an examination of Fig. 271. 



Fig. 271 shows the follicles and ova of various sizes. It is observed that the larger 

 follicles contain fully-formed ova and have a proper fibrous coat. The ova here present 

 an epithelial covering and are embedded in a mass of the epithelial lining of the follicle 

 (membrana granulosa), this mass being called the discus or cumulus proligerus. 



According to the measurements given by Waldeyer, the smallest Graafian follicles are 

 from s-fg- to 5^5- of an inch in diameter, while the largest measure from f to \ an inch. 

 At or near the period of their maturity, the follicles present several coats and are filled 

 with an albuminous liquid. The mature follicles project just beneath the surface and 

 form little, rounded, translucent elevations. The smallest follicles are near the surface, 

 and, as they enlarge, at first become deeper, as is seen in Fig. 271, becoming superficial 

 only as they approach the period of fullest distention. 



Fio. 272. Graafian follicle; magnified 30 diameters. (Luschka.) 



1, 1, stroma of the ovary; 2, 2. convoluted, cork-screw blood-vessels ; 3, fibrous wall of the follicle ; 4, membrana 

 granulosa ; 5. cumulus proligerus ; 6, zona pellucida of the ovum ; 7, vitellus of the ovum ; 8, germinal vesicle 

 with the germinal spot. 



Taking one of the largest follicles as an example, two fibrous layers can be distin- 

 guished ; an outer layer, of ordinary connective tissue, and an inner layer, the tunica 

 propria, formed of the same kind of tissue, with the difference that, as the follicle en- 



