OVULATION. 



643 



rupture of the follicle is still an unsettled question. In discussing 

 this subject Bohm and Davidoff say : 



"The manner in which the fully developed Graafian follicle 

 bursts and its ovum is freed is still a subject of controversy ; the 

 following may be said regarding it : By a softening of the cells 

 forming the pedicle of the discus proligerus, the latter, together 

 with the ovum, are separated from the remaining granulosa, and 

 lie free in the liquor folliculi. At the point where the follicle 

 comes in contact with the tunica albuginea of the ovary the latter, 

 with the theca folliculi, becomes thin, and in this region, known 

 as the stigma, the blood-vessels are obliterated and the entire 

 tissue gradually atrophies; thus a point of least resistance is 



FIG. 432. A, isolated muscle-elements of the non-pregnant uterus ; B, cells from 

 the organ shortly after delivery (Sappey). 



formed which gives way at the slightest increase in pressure within 

 the follicle, or in its neighborhood. 



"The increase of pressure within the follicle, leading to its 

 rupture, is, according to Nagel, due to a thickening of the tunica 

 mterna of the theca of the follicle. The cells of this layer pro- 

 liferate and increase in size and show yellowish colored granules. 

 This cell-proliferation leads to a folding of the tunica interna, the 

 folds encroaching on the cavity of the follicle, and causing its 

 contents to be pushed toward the stigma." 



Piersol states that the liberation of the ova usually takes 

 place at definite times, which in general coincide with the men- 

 strual epochs, one or more ova being set free at each period. This 



