ORIGIN OF THE CORPUS LUTEUM 



167 



They are often bioadly spindle-shaped or irregular in form, 

 sometimes compressed between the granulosa cells or applied 

 demilune-fashion to one of them. 



Further changes are brorght about by the great swelling of the 

 granulosa cells, which proceeds so far that the contents of the 

 follicle begin to equal and finally to exceed the capacity of the 

 contracted theca externa. The first effect of the internal pres- 

 sure is to fill whatever remains of the original follicular cavity 

 solidly with new tissue, then to compress the thecal cores of the 

 folds of the walls so that all fibrin-containing cavities and 



Fig. 20 Diagram showing outline of section of a corpus luteum about four 

 days after ovulation. X 5. pr., 'Pfropf or hernia-like bulging of contents 

 through point of rupture. 



oedematous spaces are obliterated, and the folds become merely 

 connective-tissue septa containing the remains of the theca in- 

 terna in the shape of a diminished number of theca cells en- 

 meshed by reticular fibrils; in the bases of the folds the blood- 

 vessels of the young corpus luteum enter, usually accompanied 

 by fibroblasts and fibrils proceeding from the theca externa. In 

 many young corpora lutea the swelling of the granulosa cells 

 finally causes a bulging of the contents through the outer pole 

 of the wall, at the point previously weakened by the rupture; 

 which in the prolific ovaries of the sow may be exaggerated by 



