MATURATION. 



31 



observations; thus the occurrence of fertilization during lactation when the 

 menstrual function is in abeyance; the occurrence of impregnation in young 

 girls before the onset of the menstrual periods and in women a number of years 

 after the menopause. Leopold reports the examination of twenty-nine pairs of 

 ovaries on successive days after menstruation and the finding of Graafian 

 follicles just ruptured or just ready to rupture on the eighth, twelfth, fifteenth, 

 eighteenth, twentieth and thirty-fifth days. He reports also five cases in which 

 there were no evidences of ovulation during menstruation. 



At the time of ovulation the mature follicle, which has a diameter of 8 to 12 

 mm., occupies the entire thickness of the ovarian cortex, its theca being in con- 



FIG. 19. Showing ovary opened by longitudinal incision. The ovum has escaped through the 

 tear in the surface of the ovary. The cavity of the follicle is filled with a clot of blood (corpus haemor- 

 rhagicum) and irregular projections composed of lutein cells. Kollmann's Atlas. 



tact with the tunica albuginea (Fig. 18). Thinning of the follicular wall nearest 

 the surface of the ovary, and increase in the amount of the liquor folliculi, thus 

 causing increased intrafollicular pressure, finally result in rupture of the 

 follicle through the surface of the ovary and the escape of the ovum together 

 with the liquor folliculi and some of the follicular ceils. 



The escaped ovum normally passes into the fimbriated end of the Fallopian 

 tube and so to the uterus. In exceptional cases it may remain in the tube after 

 fertilization and so give rise to a tubal pregnancy, or, falling into the abdomi- 

 nal cavity and becoming there fertilized, to an abdominal pregnancy. Both are 

 known as ectopic gestations. 



As the ovum escapes from the follicle there is more or less bleeding into the 

 follicle from the torn vessels of the theca. Closure of the opening in the 

 follicle results in a closed cavity containing a blood clot, the corpus (Fig. 19) 



