Discussion 67 



Strauss: What about those animals which do not develop an antrum, 

 and which have solid ripe follicles like the Centetinae? 



Williams: I am afraid I know nothing about them. 



Krohn: Would you attribute changes in the follicle to the vascularity 

 around the follicle, atresia starting, perhaps, at the inside of the follicle 

 because it is furthest away from the blood supply, and the effect of 

 oestrogen being related to a local increase in vascularity? 



Williams: I don't know whether any work has been done on that. 

 The awkward thing is you cannot distinguish by any means that I know, 

 which follicle is going to become atretic at any time, and which one is 

 going to proceed to ovulation, until the atresia has started. 



Zuckerman: How can one then decide whether the follicle undergoing 

 atresia which is being looked at at a given moment in a section would 

 or would not have been there if the examination had been made a fort- 

 night later, or a month later? 



Williams: I do not think you can, except from counts. The follicle 

 population diminishes as the amount of atresia increases. 



Zuckerman : That is true for the whole ovary. My question applied to a 

 specific group of follicles, which looked as though they were undergoing 

 atresia. I understood that your impression was that the process is rapid. 

 How could you know this by studying the individual atretic follicle ? 



Williams: You could, I think, only do it by vital staining methods. 

 I have not tried. 



Krohn: But you are always up against the problem of seeing the 

 same follicle twice. That is the real catch, I think. 



Amoroso : It is generally known that a fundamental difference exists 

 between the primary follicle in the normal ovaries of young rats up to 

 about 13 days of age and those of older animals following hypophy- 

 sectomy. The follicles of the young rats do not become greatly enlarged 

 in response to pituitary gonadotrophic preparations, while those of the 

 hypophysectomized animal do. From the morphological standpoint 

 there is no apparent difference between the condition of these two types 

 of follicles. The significance of this difference in follicular response is 

 unknown, but it suggests the possibility that follicular ageing may be 

 an important conditioning factor in the response of the follicle to 

 pituitary stimulation. 



Corner: I have a somewhat unorthodox notion about atresia which 

 I might mention here in order to have it knocked down. In a rhesus 

 monkey, when a very large follicle is about to ovulate, and the contained 

 ovum is in the last stages of maturation, the granulosa layer undergoes 

 a process which is very much like atresia. The nuclei of the granulosa 

 cells become pycnotic; the cells are infiltrated with fluid and become 

 fibroblastic in shape. I have called attention to this in published forms. 

 It is visible in other people's pictures, for instance in some of the pictures 

 Boling published years ago from the rat. 



Dempsey: It is also true in the rabbit. 



Corner: Yes, and I think it has been seen in one or two other species 

 also. Now in the rhesus monkey at the time of ovulation and formation 

 of the corpus luteum it is not uncommon to have some small atretic 



