CORPUS LUTEUM 



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tubes. The blood is then discharged into the vagina and is kept liquid 

 by the vaginal mucus. The mucus of the body of the uterus is viscid 

 and alkaline ; the mucus secreted at the neck is gelatinous, viscid and 

 tenacious, and also is alkaline ; the vaginal mucus is decidedly acid, 

 creamy and not viscid, containing epithelium and leucocytes. 



The third stage is that of cessation of the menses. During the latter 

 part of the second stage, the flow of blood gradually diminishes. The 

 discharge becomes rusty, then lighter in color, and in the course of 

 about twenty-four hours, it assumes the characters observed in the inter- 

 menstrual period. 



When the menstrual flow has become fully established, there is no 

 marked general disturbance, except a sense of lassitude, which may be- 

 come exaggerated if the discharge be unusually abundant. 



If the mucous membrane of the uterus is examined during the men- 

 strual flow, it is found smeared with blood, which sometimes extends into 

 the Fallopian tubes. It is then much thicker and softer than during 

 the intermenstrual period. Instead of measuring about ^ of an inch 

 (1.8 millimeters) in thickness, as it does under ordinary conditions, its 

 thickness is ^ to | of an inch (4.2 to 6.4 millimeters). It becomes more 

 loosely attached to the subjacent parts, is somewhat rugous and the 

 glands are enlarged. At the same time there are developed, in the 

 substance of the membrane, large numbers of spherical and fusiform 

 cells. This condition probably precedes the discharge of blood by sev- 

 eral days, during which time the membrane is gradually preparing for 

 the reception of the ovum. There also is a degeneration of the different 

 elements entering into the structure of the mucous membrane, including 

 the bloodvessels, this change being most marked at the surface ; and it 

 is on account of the weakened condition of the vascular walls that the 

 hemorrhage takes place. A short time after the flow has ceased, the 

 mucous membrane returns to its ordinary condition. There is a con- 

 siderable desquamation of epithelium from the uterus, with the flow of 

 blood, during the menstrual period. Sometimes, in normal menstrua- 

 tion, the epithelium thrown off is in the form of patches. 



Changes in the Graafian Follicles after their Rupture (Corpus Lutetim). 

 After the discharge of an ovum, its Graafian follicle undergoes cer- 

 tain retrograde changes, involving the formation of what is called the 

 corpus luteum. Even when the discharged ovum has not been fer- 

 tilized, the corpus luteum persists for several weeks, so that, ovulation 

 occurring every month, several of these bodies, in different stages of 

 retrogression, may sometimes be seen in the ovaries. 



For a certain time anterior to the discharge of the ovum, there is a 

 cell-proliferation from the proper coat of the Graafian follicle, and prob- 



