516 THE HUMAN BODY 



or projecting on its exterior. These, by accumulation of liquid 

 within them, have become distended to a diameter of about 4 mm. 

 (^ inch) ; finally, the thinned projecting portion of the wall of the 

 follicle, which differs from the rest in containing few blood-vessels, 

 gives way and the ovum is discharged, surrounded by some cells of 

 the discus proligerus. The emptied follicle becomes filled up with 

 a reddish-yellow mass of cells, and constitutes the corpus luteum, 

 which recedes again to the interior of the ovary and disappears in 

 three or four weeks, unless pregnancy occur; in that case the corpus 

 luteum increases for a time, and persists during the greater part of 

 the gestation period. 



Menstruation. Ovulation occurs during the sexual life of a 

 healthy woman, at intervals of about four weeks, and is attended 

 with important changes in other portions of the generative appara- 

 tus. The ovaries and Fallopian tubes become congested, and the 

 fimbriae of the latter are erected and come into contact with the 

 ovary so as to receive any ova discharged. Whether the fimbriae 

 embrace the ovary and catch the ovum, or merely touch it at vari- 

 ous points and the ova are swept along them by their cilia to the 

 cavity to the oviduct, is not certain. Having entered the Fallo- 

 pian tube the egg slowly passes on to the uterus, probably moved 

 by the cilia lining the oviduct; its descent probably takes about 

 four or five days; if not fertilized, it dies and is passed out. In the 

 womb important changes occur at or just before the periods of 

 ovulation; its mucuous membrane becomes swollen and soft, and 

 minute hemorrhages occur in its substance. The superficial layers 

 of the uterine mucous membrane are broken down, and discharged 

 along with more or less blood, constituting the menses, or monthly 

 sickness, which commonly lasts from three to five days. During 

 this time the vaginal secretion is also increased, and, mixed with the 

 blood discharged, more or less alters its color and usually destroys 

 its coagulating power. Except during pregnancy and while suck- 

 ling, menstruation occurs at the above intervals, from puberty up 

 to about the forty-fifth year; the periods then become irregular, 

 and finally the discharges cease; this is an indication that ovulation 

 has come to an end, and that the sexual life of the woman is com- 

 pleted. This time, the climacteric or " turn of life," is a critical one; 

 various local disorders are apt to supervene, and even mental de- 

 rangement. 



