70 



REPRODUCTIVE SYSTEM OF THE ADULT FROG 



Endolymphatic 

 tissue 



rior pituitary 



ars nervosa 



Optic chiasma 



Brain 



The position of the master endocrine gland — the anterior pituitary of Rana 



pipiens. 



April. Another explanation for this may be offered, namely that the 

 ovary itself may become more sensitive to such stimulation as the 

 breeding season approaches. 



The ovulation process itself consists of the rupture and the emer- 

 gence of eggs from their individual follicles. The surface of the egg, 

 separated from the body cavity by only the non-vascular theca externa, 

 is first ruptured and then the egg slowly emerges through the small 

 opening. Since the egg is known to contain a peptic-like enzyme, it is 

 believed that the pituitary hormone may activate this enzyme to 

 digest away the tight and non-vascular covering. Then by stimulation 

 of the smooth muscle fibers of the cyst wall (theca interna) the process 

 of emergence is completed. The relation of the pituitary to smooth 

 muscle activity has long been established clinically. 



It is true that the ovarian stroma shows undulating contractions at 

 all seasons, irrespective of sex activity. An egg will emerge at any 

 time from a surgically ruptured follicle. If an ovulating female is 

 etherized and the body cavity is opened, the ovary may be removed 



