Plate I. 

 The stages of follicular atresia in the ovary of the pregnant guinea pig ( x 45). 



Fig. 1. Earliest and late stage 

 of follicular atresia. 



Fig. 2. Intermediate stage of 

 follicular atresia. 



- 



Fig. 3. Final stages of folli- 

 cular atresia: thecal nodules. 



Fig. 4. Merging of the nodules 

 into the general interstitial 

 tissue. 



The microscopical preparations were kindly lent by Dr. I. W. Rowlands. 



facing page 60 



