THE PITUITARY BODY 



pars glandularis must be removed to produce the changes 

 typical of complete hypophysectomy. If 10-30 per cent of 

 the pars glandularis remains, there appear symptoms of a 

 partial pituitary deficiency. Rats appear to be normal in all 

 respects if 30 per cent or more of the pars glandularis 

 remains. 



If hypophysectomy is performed in growing rats weighing 

 80-100 g. or more, growth ceases almost immediately 

 (Smith); in younger rats, however, growth continues for a 

 time even after complete hypophysectomy (Collip, Selye, 

 and Thomson, 1933). In Figures 11-14, photographs both 

 of hypophysectomized and normal brother- or sister-rats and 

 of the same rats' skeletons are reproduced. The stunting of 

 growth is more striking in the hypophysectomized male rat 

 because the normal male littermate grows to a larger size 

 than the normal female littermate. The infantile appearance 

 of such animals depends not only upon the failure to grow but 

 also upon the persistence of the more delicate hair of the 

 young rat. Cachexia may appear earlier if the rat is older at 

 the time of hypophysectomy. Rats hypophysectomized 

 when young frequently become emaciated after weeks or 

 months; they produce heat at a slower rate and commonly 

 have a lower body temperature than normal rats. Isolated 

 tissues, such as the liver and the cortex of the kidney, if ob- 

 tained from young rats from which the pituitary body has 

 been removed, consume less oxygen than similar normal tis- 

 sues (Reiss, Hochwald, and Druckrey, 1933). The spontane- 

 ous activity of hypophysectomized rats is markedly reduced 

 (Richter and Wislocki, 1930). So far as the skeleton is con- 

 cerned, the chief changes are a shrinkage and a degeneration 

 of the epiphysial cartilage with a failure in growth (Smith). 

 The incisor teeth, which normally grow continuously, grow 

 much more slowly after hypophysectomy; the operation also 

 causes a delay in the eruption of the molars and histologic 

 changes in both the molars and the incisors (Schour and 



[44] 



