THE HISTORY AND FATE OF REDUNDANT 

 FOLLICLES 



P. C. Williams 



Imperial Cancer Research Fund, London 



The fate of redundant follicles, so far as I am capable of 

 dealing with it, is easily summarized. I believe that follicular 

 degeneration or atresia has been observed as a normal happen- 

 ing in the ovary of all mammals that have been studied. It 

 certainly occurs in all laboratory rodents and I am only 

 going to deal with these — primarily with the rat with a side- 

 glance at the guinea pig. Of the many follicles that start on 

 the path of development towards ovulation in these animals, 

 only a small minority reach the goal — most fall by the wayside. 

 It is stated that degeneration may set in at any stage in 

 follicular development, but again I am confining my remarks 

 to atresia of medium-sized and large follicles — broadly, those 

 with an antrum. This is because it is the most striking form 

 of atresia to observe and much the easiest to study. The 

 course of that atresia is familiar. 



In the guinea pig, atretic follicles show initially (Fig. 1) a 

 pyknosis of the nucleus, and disintegration, of the granulosa 

 cells bordering the antrum. The granulosa layers rapidly 

 degenerate and, as the follicle shrinks, the inner thecal cells 

 proliferate and take on a fibrocytic appearance (Fig. 2). 

 Meanwhile the ovum also degenerates and finally only the 

 theca retains its structure — it remains unaffected by the 

 secondary degeneration of the fibrocytic tissue, so that thecal 

 nodules (Fig. 3) persist giving the interstitial tissue a nodular 

 appearance before merging into general uniform interstitial 

 tissue (Fig. 4). There is much less fibrocytic proliferation from 

 the theca in the rat, but otherwise the process is exactly the 

 same. In both species, the interstitital cells so constituted. 



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