724 



THE REPRODUCTIVE ORGANS 



been in heat. There are few authentic and detailed accounts of ovarian 

 vesicles being found ruptured in the intervals of heat; and females do not ad- 

 mit the males, and never become impregnated, except at those periods. Al- 

 though conception is not confined to the periods of menstruation, yet it is 

 more likely to occur about a menstrual epoch than at other times. 



The exact relation between the discharge of ova and menstruation is not 

 very clear. It was formerly believed that menstruation was the result of 

 a congestion of the uterus arising in association with the enlargement and 

 rupture of a vesicular ovarian follicle; but though a vesicular ovarian 



FIG. 496. 



FIG. 497. 



FIG. 498. 



FIG. 496. Diagram of Uterus just Before Menstruation. The shaded portion 



represents the thickened mucous membrane. 

 FIG. 497. Diagram of Uterus when Menstruation has just Ceased, Showing the 



Cavity of the Uterus Deprived of Mucous Membrane. 



FIG. 498. Diagram of Uterus a Week After the Menstrual Flux has Ceased. The 

 shaded portion represents renewed mucous membrane. (J. Williams.) 



follicle is, as a rule, ruptured at each menstrual epoch, yet instances are 

 recorded in which menstruation has occurred where no ovarian follicle can 

 have been ruptured, and cases where ova have been discharged in amenor- 

 rheic women. It must therefore be admitted that menstruation is not de- 

 pendent on the maturation and discharge of ova. 



Observations made after death, and facts obtained by clinical investiga- 

 tion, support the view that rupture of a vesicular ovarian follicle does not 

 happen on the same day of the monthly period in all women. In the minor- 

 ity of cases it may occur toward the close or soon after the cessation of a 



