CHAPTER IV 



THE GONADOTROPIC EFFECTS OF IMPLANTS, 



EXTRACTS, AND SECRETION OF THE 



PARS GLANDULARIS 



THAT there exist significant interrelationships be- 

 tween the pars glandularis of the pituitary body and 

 the gonads is clear. Some of the evidence has already 

 been considered (studies of the physiological anatomy of the 

 pituitary, chap, i; the effects of hypophysectomy, chap. ii). 

 The great importance of these interrelationships has been 

 generally appreciated only during the past fifteen years, par- 

 ticularly since Smith, and Zondek and Aschheim (1926) re- 

 ported that "precocious sexual maturity" could be produced 

 in immature mice and rats by the implantation of the whole 

 pituitary or of the pars glandularis. Five years earlier Evans 

 and Long had demonstrated that the long-continued injec- 

 tion of simple extracts of the pars glandularis of the ox either 

 prolonged the oestrous cycles or prevented oestrus in the rat. 

 This effect appeared to be the result of an extensive luteiniza- 

 tion of the ovary. 



The discovery of the gonadotropic effects of implants or 

 extracts of the pars glandularis furnished additional concrete 

 evidence that the gonads are not autonomous structures but 

 depend upon a substance or substances, transported in the 

 blood, for at least part of their development and for their 

 maintenance. Previously, a number of investigators of the 

 physiology of the sexual glands had held the view that a hy- 

 pothetical substance (Heape called it a "generative fer- 

 ment"), elaborated elsewhere in the body, was responsible 

 for the growth, maturation, and maintenance of the gonads. 

 In the light of our present knowledge, it may be concluded 



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