PERIODICAL OVULATION. 



707 



investment. (Fig. 231.) The constant accumulation of fluid in the fol- 

 licle exerts such a pressure from within outward, that the albugineous 



Fig. 231. 



GRAAFIAN FOLLICLE, nearthe period of rupture.- a. Vesicular membrane. 6. Membrana 

 granulosa. c. Cavity of follicle, d. Egg. e. Peritoneal surface. /. Tunica albuginea. g, g. 

 Tissue of the ovary. 



Fig. 232. 



tunic and the peritoneum gradually yield before it ; until the Graafian 

 follicle protrudes from the ovary as a tense, rounded, translucent vesicle, 

 in which fluctuation can be readily 

 perceived on applying the fingers 

 to its surface. Finally, the pro- 

 cess of effusion and distension still 

 going on, the wall of the vesicle 

 yields at its most prominent por- 

 tion, the contained fluid is driven 

 out with a gush, by the elastic re- 

 action of the ovarian tissue, carry- 

 ing with it the egg, still entangled 

 in the cells of the membrana 

 granulosa. 



The rupture of the Graafian 

 follicle is accompanied, in some 

 instances, by hemorrhage from its 

 internal surface, by which its cavity 



is filled with blood. This occurs in the human species, also in the pig, 

 and to some extent in several other of the lower animals. Sometimes, 

 as in the cow, where no immediate hemorrhage takes place, the Graafian 

 follicle, when ruptured, simply collapses ; after which a slight exudation, 

 more or less tinged with blood, is poured out during the course of a 

 few hours. 



This process occurs in one or more Graafian follicles at a time, according 

 to the number of young produced at a birth. In the bitch and the sow, 

 where each litter consists of from six to twenty young ones, a similar 

 number of eggs ripen and are discharged at each period. In the mare, 

 in the cow, and in the human female, where there is usually but one 



OVART WITH GRAAFIAN FOLLICLE 

 RUPTURED: at a, the egg, just discharged, 

 with a portion of the membrana granulosa. 



