ACTIVITIES OF THE OVARY 67 



d. Vitamin E 



E-deficiency in the female rat does not upset the ovarian and general repro- 

 ductive behavior. However, established pregnancies are disturbed and are 

 terminated by resorption of the embryo (Mason, '39). In the domestic fowl, 

 unless sufficient amount of vitamin E is present in the egg, embryonic death 

 occurs during early incubation periods of the egg. 



3. The Hypophysis (Pituitary Gland) 



The ovaries experience pronounced atrophy as a result of hypophysectomy 

 in mammals and non-mammalian species. The earlier stages of follicle for- 

 mation in the higher mammalian ovary up to the stage of beginning antrum 

 formation are not so much affected, but later follicular development and inter- 

 stitial tissue growth are inhibited (Smith, P. E., '39). (See fig. 40.) 



E. Activities of the Ovary in Producing tiie Reproductive State 



1. The Ovary as a "Storehouse" of Oogonia 



The cortex of the ovary contains many young ova in various stages of de- 

 velopment. In the human ovary shortly after birth, the number of oogonia 

 in the cortex of each ovary has been estimated to reach a number as high 

 as 300,000. This figure should not be taken too literally, as the amount of 

 variability in the ovary from time to time is great and degeneration of ova 

 is a common episode. Haggstrom ('21 ) estimated that each ovary of a 22-year- 

 old woman contained 200,000 young ova. In the ovaries of young rats, Aral 

 ('20, a and b) estimated that there were on the average around 5,000 ova 

 under 20 /x in diameter. 



Without entering into the controversy (Chap. 3) relative to the rhythmic 

 origin of germ cells in the ovary, one must accept the conclusion that the 

 normal ovary has within it at all times during its reproductive life large num- 

 bers of oogonia in various stages of development. Thus the ovary, aside from 

 its other activities, functions as a storehouse and nursery for young oogonia. 

 Relatively few of these oogonia develop into mature eggs in the mammals. 

 For example, the reproductive life of the human female occurs from about 

 the age of 10 or 14 years to about 48 years. If one egg per monthly cycle 

 is discharged from the ovary which is functional during that cycle, only about 

 400 eggs would be matured in this way. The number would be less if preg- 

 nancies intervened. If one accepts the figures given by Haggstrom, an enor- 

 mous number of eggs of the human ovary never reach their potential goal. 

 Similarly, according to Corner ('43) : "The most prolific egg producer among 

 mammals, the sow, might possibly shed a total of 3,000 to 3,500 eggs, allow- 

 ing ten years of ovarian activity not interrupted by pregnancy, and assuming 

 the very high average of 20 eggs at each three weekly cycle, but she has vastly 

 more than this in the ovaries at birth." 



