THE PITUITARY BODY 



thymus.'' — If the young mammal (rat or dog) is hypophysec- 

 tomized, the thymus undergoes a more rapid involution than 

 is normally the case (Smith, 1930, and Houssay and Lascano- 

 Gonzalez, 1934). However, hypertrophy of the thymus has 

 been observed in rats hypophysectomized when adult (Richter 

 and Wislocki, 1930). References to other observations in 

 hypophysectomized dogs will be found on pages 64-65. 



The administration of anterior-lobe extracts or implants 

 usually has been found to hasten the involution of the 

 thymus — a change which has also been observed after the 

 administration of oestrin (fowl — Wulzen, 1914, fed fresh 

 anterior lobe; duck, Schockaert, 1930-31; rat, Golding and 

 Ramirez, 1928, Tsunoda, 1934; guinea pig, Watrin and 

 Florentin, 1932). An exceptional case is that of mice with 

 hereditary dwarfism. The administration of a growth-pro- 

 moting extract of the anterior pituitary to such mice causes 

 a marked proliferation of the parenchyma of the thymus 

 (Kemp, 1934). 



The interrelationship between the anterior pituitary and the 

 adrenal glands. — The effect of hypophysectomy on the ad- 

 renal glands of the rat is illustrated by the data and photo- 

 micrographs of Figures 50-51. Striking changes occur in the 

 cortex in which the atrophic change appears to be due to a 

 cellular atrophy; fat is distributed in a narrow zone rather 

 than throughout the cortex (Smith). ^ Although there may 

 also occur some atrophy of the medulla, the microscopic ap- 

 pearance of the latter is not appreciably altered. Descriptions 

 of the effect of hypophysectomy on the adrenals of other ani- 

 mals will be found in chapter ii. Direct or indirect interrela- 

 tionships between the pituitary and the adrenals are sug- 

 gested by other experiments in which hypophysectomized 

 rats were used. Smith, Greenwood, and Foster (1927) found 



'' For other references see the Index. 



5 Smith (1930) concluded that the atrophy of the adrenal was greater than could 

 occur merely as a result of a thyroid deficiency. 



[280] 



