THE PITUITARY BODY 



data of Donaldson (1924), however, shows that the weight 

 of the brain of an immature rat (50 g.) may be three-fourths 

 that of an adult rat (350 g.). 



Smith estimated that, under the most favorable condi- 

 tions, the life-span of the hypophysectomized rat is about 

 one-half that of the normal rat. 



Fig. 



-The skeletons of the rats shown in Figure 13 



xAs in amphibia, reptiles, and birds, hypophysectomy in the 

 rat is rapidly followed by atrophy and degenerative changes 

 in the gonads and their related structures. The gross and mi- 

 croscopic appearances of the testis of a hypophysectomized 

 and a normal rat are shown in Figures 15 and 16. The regres- 

 sive changes involve not only the germinal epithelium but 

 also the interstitial cells, so that a marked atrophy of the 

 seminal vesicles, prostate, etc., occurs (see Figs. 17 and 18). 



[48] 



