THE PITUITARY BODY 



injury of the brain, however, can be avoided. In the absence 

 of hemorrhage and infection, hypophysectomy in the dog as 

 a rule is quickly followed by the death only of those animals 

 in which the gland has been approached from the temporal 

 side of the cranium. By skilled hands, however, the operation 

 by either approach has been satisfactorily performed (e.g., 

 Aschner, 1912, Dandy and Reichert, 192.5; Reichert, 1928; 

 McLean, 1928). 



The ejects of the removal of the pars glandularis. — In the dog, 

 as in the rat, the important effects of the removal of the 

 pituitary body are due to the removal of the pars glandularis. 

 Those who formerly believed that hypophysectomy was fol- 

 lowed shortly by death attributed this result to the extirpa- 

 tion of the pars glandularis. In the cases of some of their 

 dogs, however, they beheved that, because of the incomplete 

 removal of the pars glandularis, the animals lived and later 

 exhibited the symptoms of a pituitary deficiency. Aschner 

 (191 2) concluded that hypophysectomy in the dog is physio- 

 logically complete if no remnants of the pars glandularis can 

 be found grossly; he also stated that no symptoms of pitui- 

 tary deficiency appear if about one-third of the pars glandu- 

 laris remains — an estimate very close to that made by Smith 

 (1932) in his study of partial hypophysectomy in the rat. 



The principal changes, clearly attributable to hypophysec- 

 tomy in dogs, resemble those in hypophysectomized rats. As 

 a result of hypophysectomy, puppies cease to grow but may 

 increase somewhat in weight due to the deposition of fat. 

 Unlike normal brothers or sisters, their skeletons scarcely 

 change in size, the epiphyses remain open, and the first denti- 

 tion persists for months after it has been replaced by the sec- 

 ond dentition in normal dogs. The skin and hair remain in- 

 fantile. The animals are sluggish and inactive.^ The body 

 temperature is 1-1.5° ^- lower than that of normal dogs; the 



» Conditioned reflexes in hypophysectomized dogs have been compared with 

 those in normal dogs by Kriaschew (1933). 



[60] 



