REPRODUCTIVE ORGANS IN THE FEMALE. 305 



mated that there are thirty-five thousand eggs or 

 ova to each ovary. Only a small number of these 

 ripen and become discharged as mature eggs. The 

 extrusion of these eggs from the ovary is known as 

 ovulation, and in woman is supposed to occur during 

 the menstruation period, one from each ovary. 

 Menstruation in a normal woman extends generally 

 over a period of thirty-two years, between the ages of 

 thirteen and forty-five. If thirteen eggs ovulate 

 yearly from each ovary, there will be a possible total 



Follicvlar cavity. 



Nucleus. 



Fig. 221. Young Graafian follicles: a, follicle with one layer of epithe- 

 lial cells; b, follicle with two layers of epithelial cells. 



of eight hundred and thirty-two that may ripen dur- 

 ing the life of a woman, allowing no interruption for 

 pregnancies. After the menopause, ovulation is 

 supposed to cease. 



The Ripe Graafian Follicle. It has already been 

 stated that only a small number of the young ova 

 ripen and ovulate. These mature in the following 

 manner: The ovum of such follicles occupies a cen- 

 tral position where it accumulates food and grows 

 into a large spherical cell. The investing epithelium 



