152 



BIOLOGY OF THE LABORATORY MOUSE 



this cavity disappears. At the beginning of this process mitotic figures are 

 seen among the theca interna cells as well as among the granulosa cells. 





Ruptured surface 

 Blood vessel 



Germinal epithelium 



Granulosa cells 



, — i_«;.,»^ ^- Theca interna 



Fig. 78. — Ruptured follicle. (X62.) 



Theca externa 



Germinal epithelium 



Central cavity 



Lutein cells 



Trabecula 



Theca externa 



Fig. yq. — -Young corpus luteum. 



Later the granulosa cells rapidly hypertrophy with resulting increase in size 

 of the corpus luteum as a whole. While the small granulosa cells have oval 



