OVULATION . 349 



the ovarian ligament. An ovary is about three-quarters of an 

 inch long, a half-inch wide, and shaped like an almond (Figs. 

 224, 226). 



The ovaries are covered with peritoneum (except at the border 

 where vessels enter and leave). 



Structure of the ovary. A collection of connective-tissue 

 fibers enclosing many vessels and nerves, and a multitude of little 

 ovisacs (egg sacs) called Graafian follicles. These follicles are 

 at first microscopic in size, but when developed they may be seen 

 by the naked eye. Each one contains an ovum, or egg. 



Ovulation. As the follicle 

 with its ovum grows in size it 

 approaches the surface of the 

 ovary, and when it is mature 

 the sac ruptures and the ovum 

 escapes, to be taken by the uter- 

 ine tube to the uterus, from 

 which it is discharged through 



the vagina, usually with a quan- FIG. 226. OVARY WITH MATURE 



GRAAFIAN FOLLICLE ABOUT READY TO 



f 

 c 



BURST (Ribomont-Dessaignes-Lewis.) 



The function of the ovary 

 (ovulation) begins with puberty, which is the maturing of the 

 pelvic organs and mammary glands. It is usually established at 

 about fourteen years of age (earlier in warm climates, later in 

 cold). From that time the development of at least one ovum 

 occurs in (about) every twenty-eight days until the menopause is 

 established. 



Menstruation is the periodical discharge of blood from the 

 uterus. The mucous membrane thickens and sheds its superficial 

 cells, which are renewed after the flow ceases. This probably 

 accompanies ovulation. When an impregnated ovum reaches the 

 uterus menstruation is suspended. 



The cessation of menstruation is the menopause or climacteric. 

 It often occurs at about forty-five years of age and may be as 

 late as fifty or over. It is followed by gradual atrophy of the 

 generative organs. 



Corpus luteum is the name given to a yellow substance which forms in the 

 ruptured Graafian follicle. It ordinarily shrinks and disappears within a 

 month. Immediately after the rupture the follicle fills with blood; this 

 forms the corpus hemorrhagicum, changes to the corpus luteum and this in 



