CHAPTER II 



THE REGULATION OF GROWTH BY THE 

 PITUITARY BODY 



NO INVESTIGATOR has succeeded in preparing a 

 satisfactorily "pure" growth-promoting extract of 

 the pituitary body. There is general agreement that 

 the pituitary, among endocrine glands, is the most important 

 regulator of growth; but whether this regulation is effected 

 by a specific "growth-promoting hormone" or by direct or 

 indirect combined effects of other pituitary hormones, such 

 as the lactogenic and the thyrotropic hormones, remains an 

 undecided issue. 



Particularly Riddle and his colleagues oppose the view 

 that a specific growth-promoting hormone is secreted by the 

 anterior pituitary. They suggest that the combined action 

 probably of the thyrotropic and lactogenic hormones ac- 

 counts for the principal somatic effects of growth-promoting 

 extracts and have put forward suggestive but not conclusive 

 evidence in favor of this view. All the potent extracts which 

 they have examined contained both of these hormones to 

 which they attribute any calorigenic effects such extracts 

 may have (Riddle and others, 1936). Bates and his co- 

 workers (1937) found that the injection of "relatively highly 

 purified preparations" of the lactogenic hormone into hypo- 

 physectomized pigeons caused body-growth as well as a 

 marked increase in the weight of the liver.' Similar effects 

 together with a growth of the intestine were observed in 

 normal pigeons. The only studies which have been consid- 



' Effkemann and Herold (1935) concluded that extracts of organs other than 

 the pituitary may cause moderate or marked hypertrophy of the Hver in the pigeon 

 and rat without striking associated changes in body-weight. However, they believed 

 that pituitary extract brought about specific morphological changes. 



