GRAAFIAN FOLLICLES. 275 



structures are developed in and surrounding these cells, a* 

 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, be- 

 tween the smallest primordial follicles, -g-J-g- of an inch, and 

 the largest, nearly \ an inch in diameter. In follicles that 

 have attained any considerable size, we have the fully-devel- 

 oped ova, one in each follicle, except in very rare instances, 

 when there are two, 1 and these ova have a pretty uniform di- 

 ameter of about Y^ of an inch. In the process which culmi- 

 nates in the discharge of the ovum into the fimbriated ex- 

 tremity of the Fallopian tube, the Graafian follicle gradually 

 enlarges, becomes distended with liquid, and finally breaks 

 through and ruptures upon the surface of the ovary. It be- 

 comes 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 dif- 

 ferent portions of the ovary and the follicles and ova of vari- 

 ous sizes, by an examination of Fig. 25. 



Fig. 25 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 epi- 

 thelial 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, 9 the 



1 Schro'n has observed two and even three ova in a single follicle, in some of 

 the lower animals. In four hundred examinations of ovaries of the cat, he 

 found one follicle with two, and one follicle with three ova. In eighty examina- 

 tions in the bitch, he found a single follicle with two ova ; but he found no other 

 examples of this. (SCHRON, Beitrag zur Keiitniss der Anatomic und Physiologic 

 des Eierstocks der Sdugethiere. Zeitschrift fur wissenschaftliche Zoologie, Leipzig, 

 1863, Bel. xii., S. 409, et seq.) Kolliker noted two ova in a single follicle, in the 

 human subject. (Elements d'histologie humaine, Paris, 1868, p. 705.) 



a WALDEYER, in STRICKER, Manual of Human and Comparative Histology, 

 The New Sydenham Society, London, 1872, vol. ii., p. 207. 



