PHYSIOLOGICAL PEOPERTIES OF GONADS 



141 



as well as those follicles near the stage of maturation when cor- 

 pora lutea are formed, do not remain in this stage, but undergo 

 atretic changes. Also before the onset of sexual maturity (in 



Fig. 5 Follicle about the stage of maturity (from same graft as figs. 3 and 4). 



Fig. 6 Poriion of mature follicle with ovum and polar body (from 230-day 

 ovarian graft of male 49 C) . The ovum is surrounded by the degenerating discus 

 proligerus. dp, discus proligerus;/c, follicular cavity; 0, ovum; p6, polar body. 



the rat) the follicles proceed in their development to about the 

 stage of maturation^ — i. e., the follicular cavity is well devel- 

 oped and the ovum is surrounded by a distinct discus proligerus 



