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TEXT-BOOK OF EMBRYOLOGY. 



onset of the menstrual periods and in women a number of years after the meno- 

 pause. 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- 

 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 



Point of rupture 



Lutein cells 



Corpus haemorrhagicum 



Blood vessel of theca 



Cavity of follicle 



Theca folliculi 



Ovarian stroma 



Stratum granulosum 



FIG. 20. From section of human ovary, showing early stage in formation of corpus luteum. 



Kollmann's Alias. 



causing increased intrafollicular pressure, are followed by the 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 cells. 



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 abdominal 

 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 hamorrhagicum, 



