32 



TEXT-BOOK OF EMBRYOLOGY. 



h&morrhagicum, which then becomes gradually transformed into the corpus 

 luteum. 



The transformation of the corpus haemorrhagicum into the corpus luteum 

 (Figs. 20 and 21) is brought about by ingrowths of strands of connective tissue 

 from the inner layer of the theca and the replacement of the remainder of the 

 clot by large yellowish cells containing pigment (lutein granules) and known as 

 lutein cells. The lutein cells are considered by some as derived from the con- 

 nective tissue cells of the theca, by others as due to proliferation of the cells of 

 the stratum granulosum. Degeneration and absorption of the tissues of the 



Point of rupture 



Lutein cells 



Corpus haemorrhagicum 



Blood vessel of theca 



Cavity of follicle 



Theca folliculi 



Ovarian stroma 



Stratum granulosum 



FIG. 20. From section of human ovary, showing early stage in formation of corpus luteum. 



Kollmann's Atlas. 



corpus luteum follows, resulting in shrinkage, and loss of its characteristic 

 yellow color. The whitish body resulting is known as the corpus albicans and 

 is itself in turn either wholly absorbed or represented only by a small scar of 

 fibrous tissue. 



The rapidity with which the changes, both constructive and destructive, 

 take place in the corpus luteum, appears to be largely dependent upon whether 

 the egg which escaped from the follicle is or is not fertilized. If ovulation is not 

 followed by fertilization the corpus luteum reaches the height of its development 

 in about twelve days, and within a few weeks has almost wholly disappeared. 

 If, on the other hand, pregnancy supervenes, the corpus luteum' becomes much 

 larger, does not reach its maximum development until the fifth or sixth month 

 and is still present at the end of pregnancy. The above differences have led to 

 the distinction of the corpus luteum of pregnancy or the true corpus luteum, and 



