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HAND-BOOK OF PHYSIOLOGY. 



takes place, its walls appear thickened on the interior by a reddish gluti- 

 nous or fleshy-looking substance. Immediately after the rupture, the 

 inner layer of the wall of the vesicle appears pulpy and flocculent. It is 

 thrown into wrinkles by the contraction of the outer layer, and, soon, 

 red fleshy mammillary processes grow from it, and gradually enlarge till 

 they nearly fill the vesicle, and even protrude from the orifice in the ex- 

 ternal covering of the ovary. Subsequently this orifice closes, but the 

 fleshy growth within still increases during the earlier period of pregnancy, 

 the color of the substance gradually changing from red to yellow, and its 

 consistence becoming firmer. 



The corpus luteum of the human female (Fig. 399) differs from that 

 of the domestic quadruped in being of a firmer texture, and having more 

 frequently a persistent cavity at its centre, and in the stelliform cicatrix, 

 which remains in the cases where the cavity is obliterated, being propor- 

 tionately of much larger bulk. The quantity of yellow substance formed 



FIG. 399. Corpora lutea of different periods. B, Corpus luteum of about the sixth week after 

 impregnation, showing its plicated form at that period. 1, substance of the ovary; 2. substance of 

 the corpus luteum ; 3, a greyish coagulum in its cavity. (Peterson.) A, corpus luteum two days after 

 delivery; D, in the twelfth week after delivery. (Montgomery.) 



is also much less: and, although the deposit increases after the vesicle has 

 burst, yet it does not usually form mammillary growths projecting into 

 the cavity of the vesicle, and never protrudes from the orice, as is the 

 case in other Mammalia. It maintains the character of a uniform, or 

 nearly uniform, layer, which is thrown into wrinkles, in consequence of 

 the contraction of the external tunic of the vesicle. After the orifice of the 

 vesicle has closed, the growth of the yellow substance continues during the 

 first half of pregnancy, till the cavity is reduced to a comparatively small 

 size, or is obliterated; in the latter case, merely a white stelliform cicatrix 

 remains in the centre of the corpus luteum. 



An effusion of blood generally takes place into the cavity of the 

 Graafian vesicle at the time of its rupture, especially in the human sub- 

 ject, but it has no share in forming the yellow body; it gradually loses 

 its coloring matter, and acquires the character of a mass of fibrin. The 

 serum of the blood sometimes remains included within a cavity in the 

 centre of the coagulum, and then the decolorized fibrin forms a mem- 



