88 



THE VERTEBRATE OVARY AND ITS RELATIONSHIP TO REPRODUCTION 



Fig. 51. Effects of estradiol (estrogen) upon the female genital tract of the opossum. 

 (After Risman, J. Morphol., 81.) (A) Reproductive tract of an ovariectomized female. 

 (B) Hypertrophied condition of a female experiencing the normal estrous changes. (C) 

 Reproductive tract of an ovariectomized female injected with estradiol (0.9 mm.) 36 

 days after the ovaries were removed. 



(fig. 40). This evidence suggests that the pituitary gonadotrophins, FSH and 

 LH, control the development of the ovary and, through their influence upon 

 the ovarian tissues, promote the secretion of estrogen with the subsequent 

 hypertrophy of the female accessory reproductive structures. It is to be ob- 

 served that it is not at all clear that FSH in pure form is able to elicit estrogen 

 production without the presence of LH (ICSH). (See Evans and Simpson 

 in Pincus and Thimann, '50, p. 355.) 



4) Effect of Estrogen upon the Female Mammal. The changes in the 

 mammalian accessory reproductive organs produced by estrogen are marked. 

 An increase in vascularity and great hypertrophy of the accessory structures 

 result from its injection into ovariectomized females. (See figs. 51, 52, 53.) 

 Increased irritability and activity of the accessory structures also occur. This 

 increased activity appears to be an important factor in the transportation of 

 sperm upward within the female accessory organs to the region where the 

 egg awaits the sperm's arrival. 



The alterations in behavior of the female as a result of estrogen stimulation 

 may be considerable. Females actually seek the presence of a male during 

 the period of strong estrogenic influence. The long journey of the female fur 

 seal to the mating grounds in the Bering Sea, the bellowing and tireless search 

 of the cow moose, the almost uncontrollable demeanor of seeking the male 

 on the part of the female dog or of the cow in "heat" — these are a few illus- 

 trations of the regnant power of this stimulant upon the female mammal. 



