CORPORA LUTE A. 185 



and finally the vesicle ruptures, permitting the ovule to escape 

 from the ovary and pass into the oviduct. The discharge of 

 an ovule in this manner takes place regularly and periodically, 



FIG. 72. 





Human ovule and its surroundings in the ovary (Nagel). a, g, vitelline mem- 

 brane (zona pellucida and zona radiata) ; b, c, vitellus or cytoplasm of ovule ; 

 d, nucleus or germinal vesicle ; e, corona radiata ; /, cells of cumulus ovigerus. 



comprising the process called ovulation, which stands in a 

 definite relation with menstruation. 



Corpora lutea : The ruptured Graafian follicle after ovula- 

 tion undergoes a series of retrograde changes, the resulting 

 structure being called a corpus hiteum. 



The wound or cavity of the emptied Graafian follicle 

 becomes filled with blood from the ruptured vessels, and the 

 cells of the tunica granulosa proliferate abundantly. From 

 the fatty degeneration of cells or the transformation of haemo- 

 globin into haematoidin the structure acquires a yellow color, 

 whence its name. Into the mass of epithelial cells and blood- 

 clot grow, from the ovarian stroma, vascular processes of 

 connective tissue (granulations), giving the body a lobed or 

 radiate appearance. By the continued growth and contrac- 



