EFFECTS ON THE HYPOPHYSIS 



453 



more homogeneous and often finely vacuolated in appearance. Around 

 pycnotic nuclei it is usually more strongly basopholic, and is much reduced in 

 volume in the atrophic areas above mentioned. 



''The colloid which occurs normally in the pars nervosa and in the hypophy- 

 seal cavity (residual lumen) appears unaffected by inanition. 



" In the pars anterior, the changes during inanition are quite variable. Some 

 areas may remain nearly normal, while others, even in the same gland, show 

 extreme changes of atrophy and degeneration. The cytoplasm is usually 

 reduced in volume (as above shown) and is frequently much vacuolated. The 

 structure becomes sparsely granular and there is a marked tendency to loss of 

 the specific staining reactions, so that the strongly chromophilic cells become 

 weakly chromophilic or even chromophobic. The nuclear changes are likewise 

 variable, but there is a very general tendency to hyperchromatism often reaching 

 a definite pycnosis. Karyorrhexis and karyolysis are rare. 



JUioll 



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Fig. 115. — A small portion of the pars anterior of the hypophysis in a normal albino rat 

 (J. 1.2) 3 weeks old. Most of the cells are of the faintly basophilic type. Some eosinophilic 

 cells are indicated by darker staining. A few chromophobic cells are shown, a group of four 

 near the left margin. Zenker fixation; hematoxylin-eosin stain. Drawn with the aid of a 

 camera lucida. X760. (Jackson '17.) 



"Upon refeeding one-half week after the maintenance period (three to 

 twelve weeks of age), the hypophysis still retains the typical inanition structure, 

 although mitosis and growth have begun. After one week of refeeding, some 

 areas have become nearly normal, and after two weeks the normal structure pre- 

 ponderates. After four weeks, the greater part of the hypophysis appears 

 nearly normal, although atrophic areas may persist for indefinite periods. 

 Recovery is improbable in cells whose nuclei have reached advanced pycnosis." 



Some of the characteristic changes in the pars anterior of young albino rats 

 during inanition are shown in Figs, n 5-1 17. Fig. 115 shows the normal 

 structure at three weeks of age; Fig. 117 represents the normal structure at ten 

 weeks; while Fig. 116 shows the atrophic and degenerative changes found in a 

 rat held at constant body weight by underfeeding from three to ten weeks 

 of age. 



