IMPREGNATION OF MAMMALIA. 713 



ceeding ovisac with the ripening ovum has begun to protrude 

 from the surface of the ovary, the old ovisac has lost its yellow 

 colour, with much of its size, and has retired inward. This move- 

 ment, with the collapse of the wall, depresses the cicatrix of the 



560 



Corpus luteum,' after escape of ovum, Human, ccxlvi". 



aperture ; and by these successive shrinkings and cicatrisations 

 of the burst ovisacs, the ovary becomes marked by pits and fur- 

 rows in advanced life. If the expelled ovum be not impregnated, 

 the changes of the ovisac into the yellow convolute cavity, then 

 into a small white stellate body, may occupy two months in the 

 Human subject ; but, if the maturation of successional ova be 

 delayed by impregnation and its consequences, the first change 

 goes on to a greater degree, and the ' corpus luteum ' is not obliter- 

 ated in less time than from thirteen to fourteen months : the 

 inner coat, or original ovisac, is more thickened by a larger de- 

 posit of yellow oil-granules; 56l 

 it becomes more deeply pli- 

 cated, is then compacted into 

 a yellowish mass, and gains an 

 adventitious white lining mem- 

 brane, fig. 561. Rarely until 

 after full gestation and deli- 

 very is the cavity obliterated : 

 it is then represented by a 

 stellate linear figure surround- 

 ed by the 'COrpUS luteum,' Section of Human ovary with' corpus luteum,' after 

 i • i . i,. .i . it impregnation, ccxlvi". 



which is ultimately absorbed. 



§ 398. Impregnation. — ■ After coitus the spermatozoa find their 

 way to the Fallopian tubes, or oviducts, and might come 

 into contact with the ovarian ovum, through the opening in 



