THE PITUITARY BODY 



normal anatomical condition and raises the metabolic rate, 

 which is low chiefly because of a thyroid deficiency subse- 

 quent to hypophysectomy. 



The effects of administration of anterior pituitary tissue or 

 extracts. — Smith (1926, 1930) clearly demonstrated that the 

 atrophic thyroid of the hypophysectomized rat could be re- 

 stored to normal both grossly and microscopically by the ad- 

 ministration of fresh homoplastic implants. Similar results 



Fig. 46. — Gross appearance of" ihe lobes of the th.roid of' a hypophysectomized 

 rat and of a normal littermate control rat. The thyroid lobes of the operated animal 

 are to the left. 



following the use of extracts in other species such as the dog 

 have been reported (Houssay, Biasotti, and Magdalena, 



1932)- 



The response of young normal mammals differs enormously 

 among different species. There is some evidence that thy- 

 roid sensitivity to anterior pituitary extracts is inversely pro- 

 portional to the amount of thyrotropic hormone in the ani- 

 mal's own pituitary (see the results of Loeb, 1932; and Loeb 

 and Friedman, 1933). None more sensitive than the young 

 guinea pig has so far been found; the young rat, on the other 



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