568 OVULATION AND FUNCTION OF MENSTRUATION. 



accordingly always situated at the most superficial portion of the 

 follicle, and advances in this way toward the surface of the ovary. 

 As the period approaches at which the egg is destined to be dis- 

 charged, the Graafian follicle becomes more vascular, and enlarges 

 by an increased exudation of serum into its cavity. It then begins 



Fig. 185. 



Fig. 186. 



GRAAFIAX FOLLICLE, near the period of rupture n. Mernbraneof the vesicle. 1> Membrnna 

 granulosa. c. Cavity of follicle, d. Egg. e. Peritoneum. /. Tunica albugiuea. y, y. Tissue of 

 the ovary. 



to project from the surface of the ovary, still covered by the albu- 

 gineous tunic and the peritoneum. (Fig. 185.) The constant accu- 

 mulation of fluid, however, in the follicle, exerts such a steady and 

 increasing pressure from within outward, that the albugineous tunic 

 and the peritoneum successively yield before it ; until the Graafian 

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



vesicle, in which the sense of 

 fluctuation can be readily per- 

 ceived 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 promi- 

 nent portion, the contained fluid 

 is driven out with a gush, by the 

 reaction and elasticity of the 

 neighboring ovarian tissues, car- 

 rying with it the egg, still en- 

 OVARY WITH GRAAFIAN FOLLICLE tangled in the cells of the pro- 



RTPTURED: at a, egg just discharged with a -i- Y \r 



portion of membraua granulosa. llgerOUS Q1SK. 



The rupture of the Graafian 

 vesicle is accompanied, in some instances, by an abundant hemor- 



