86 THE VERTEBRATE OVARY AND ITS RELATIONSHIP TO REPRODUCTION 



The structural formulae of estradiol and of estrone are as follows: 



HO' 



Estradiol Estrone 



2) The Ovary as the Normal Source of Estrogen in the Non-pregnant 

 Female. Aside from the fact that estradiol and estrone are readily extracted 

 from the ovary, certain experiments tend to focus attention on the ovary as 

 an important site of estrogen production. For example, the removal of the 

 ovaries of a normal, adult female mammal causes the accessory reproductive 

 organs to undergo profound atrophy. The administration of appropriate 

 amounts of estrogen will restore the accessories of such a female to the con- 

 dition normal for the resting state. (Consult Pincus, '50, in Pincus and 

 Thimann, Chap. I.) The injection of follicle-stimulating hormone with small 

 amounts of the luteinizing hormone into the diestrous (i.e., sexually-resting) 

 female with intact ovaries results in follicular development within the ovaries, 

 accompanied by hypertrophy of the accessory reproductive organs to the full 

 estrous condition ( Nelsen and White, '4 1 ; Pincus, '50, in Pincus and Thimann ) . 

 These and similar experiments point to the ovary as the main site of estrogen 

 formation in the body of the non-pregnant female. 



The exact structures of the ovary responsible for estrogen elaboration are 

 not easily determined. Estrogen is found in all parts of the ovary, but certain 

 observations and experimental results suggest that it is formed in relation 

 to the follicular tissues and also by the so-called interstitial tissue of the 

 ovary. For example, when tumors occur within the thecal tissue of the egg 

 follicle in women who have experienced the menopause, there is often an 

 accompanying hypertrophy of the accessory organs. This relationship suggests 

 that thecal gland tissue of the follicle may have the ability to elaborate estro- 

 gen (Geist and Spielman, '43). On the other hand, the normal hypertrophy 

 of the granulosa cells of the egg follicle during the normal reproductive cycle, 

 with the presence of follicular fluid containing estrogen in the antral space 

 of the follicle, points to the granulosa cells as a possible source of estrogen. 

 Also, it has been observed that tumorous growths of the granulosa cells of 

 the follicle produce an excess of estrogenic substance (Geist and Spielman, 

 '43). Thus, these observations point to the granulosa cells of the egg follicle 

 of the ovary as being capable of estrogen formation. Another possible source 

 of estrogen secretion in the ovary is the interstitial cells, derived in part 

 from theca interna tissue and atretic follicles. These cells are large polyhedral 

 epithelioid cells scattered between the follicles. Their growth appears to be 

 directly stimulated by the injection of pure luteinizing hormone (LH; ICSH) 



