454 



PHYSIOLOGY OF GONADS 



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Fig. 7.O. Imuiuturu li.ypophy.sectomized rat treated with Arniuui - i>il. (iiauulo.sa ha^ 

 proliferated and follicles have developed antra. The theca is diffeientiated but the intersti- 

 tium is deficient. (Couitesy of Dr. R. M. Melampy.) 



clearly the local stimulating effect of estro- 

 gens with the ovary, as well as the systemic 

 effect by way of the pituitary. 



If estrogen administration to immature or 

 to hypophysectomized immature rats is con- 

 tinued 7 to 10 days, the granulosa of the 

 stimulated follicles degenerates. This atretic 

 process differs from natural atresia in that 

 it seems to start peripherally rather than 

 centrally. The oocytes do not fragment or 

 give off polar bodies as frecjuently as do 

 oocytes in normally atretic follicles. It seems 

 that the stimulatory effect of estrogen on 

 the granulosa is very temporary. Its din-a- 

 tion, however, is long enough to be coni- 

 ])atible with the noi'inal pi'ocess of matura- 

 tion and ovuhitiou. 



Before concluding the subject, a certain 

 amount of back-tracking may be dcsii'able. 

 One of the first suggestions to be made by 

 Edgar Allen (1922; see also the biogi'aphic;il 

 sketch in this book) was tliat the ovum is 



the dynamic center of the follicle. If the 

 suggestion is placed in the context that has 

 since been developed, the sequence of events 

 would l)e an inductive influence of the 

 oocyte on the membrana granulosa, a con- 

 tinued inductive influence (oocyte or mem- 

 brana granulosa?) on the surrounding con- 

 nective tissue cells until the theca interna 

 is formed,- and then the secretion of estro- 



'Resuhs obtained by Genther (1931), Schmidt 

 (1936), Humphreys and Zuckerman (1954). and 

 Wcstman (1958) suggest that a similar functional 

 iclationship exists between the granulosa and in- 

 terstitial cells. According to Genther, x-ray-iujured 

 o\aries composed of interstitial cells produced es- 

 trogen only if a growing follicle was present. The 

 in\oluted condition of the uteri in rabbits in wliich 

 all oocytes and f()llicl(>s iiad been destroyed by 

 x-rays led Humphreys and Zuckerman to conclude 

 that the ovaries of these animals were not produc- 

 ing estrogen. The results reported by Westman 

 suggested tliat interstitial cell function continues 

 only lor .1 limited jieriod after x-ray-induced de- 

 generation of the granulosa cells. The results from 

 an ingenious investigation by Ingram (1957) ar( 



