CHAPTER V. 



THE CORPUS LUTEUM, AND ITS CONNECTION WITH 

 MENSTRUATION AND PREGNANCY. 



AFTER the rupture of a Graafian follicle at the menstrual period, 

 there is left in the ovary a bloody cavity, which is subsequently 

 obliterated by a process somewhat similar to the healing* of an abscess. 

 The office of the Graafian follicle is to provide for the formation and 

 growth of the egg- in the ovary. After the discharge of the egg, the 

 follicle has no further function to perform ; and it then passes through 

 a process of obliteration, as an organ which has become obsolete. 

 While undergoing this change, it is at one time converted into a 

 solid, spheroidal body, called the corpus luteum ; a name derived from 

 the yellow color acquired during its formation. 



In quadrupeds, the corpus luteum is characterized by peculiarities 

 of size, color, growth, and disappearance, which are distinctive for 

 each species ; although the general course of its formation and atrophy 

 is the same in all. In the human female it is marked by a moderately 

 large size, a brilliant yellow hue at certain periods of its development, 

 and the presence of blood in its central cavity, distinguishable for two 

 or three weeks after the rupture of the follicle. The details of its 

 growth and retrocession, which follow a regular course during the 

 normal recurrence of the menstrual periods, are modified by the ex- 

 istence of pregnancy. In the first instance, it is known as the corpus 

 luteum of menstruation ; in the second as the corpus luteum of preg- 

 nancy. 



Corpus Luteum of Menstruation. 



In the human female, during menstruation, at or immediately after 

 the discharge of the egg, a somewhat abundant hemorrhage takes place 

 from the inner surface of the Graafian follicle, by which its cavity is 

 filled with blood. The blood soon coagulates, as it would if extrava- 

 sated elsewhere, and the coagulum remains enclosed by the walls of 

 the follicle. The opening by which the egg has escaped is usually a 

 rounded perforation, not more than one millimetre in diameter; and 

 a slender probe, introduced through this opening, passes directly into 

 the cavity of the follicle. If the follicle be opened at this time by a 

 longitudinal incision through the ovary (Fig. 169), it will be seen to 

 form a spheroidal cavity, between one and two centimetres in diameter, 

 containing the soft, recent, dark colored coagulum. The coagulum has 

 no organic connection with the walls of the follicle, but lies loose in 



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