INANITION OF THYROID IN RATS 349 



gland may show but little loss in absolute weight, although 

 there has been a marked atrophy of the parenchyma. 



In the adult rats subjected to acute and chronic inanition, the 

 changes in the structure of the thyroid gland are likewise varied, 

 but in general similar to those found in the younger rats. The 

 interpretation of the changes in the older rats is more difficult, 

 on account of the frequent occurrence in the normal (control) 

 rats of degenerative changes somewhat similar to those found in 

 advanced stages of inanition. 



These changes, involving desquamation and degeneration of 

 the follicular epithelium, have frequently been observed in the 

 thyroids of rats both normal and under various abnormal condi- 

 tions. They also occur as pathological changes in various 

 other glands. It is suggested that the similarity of these cell- 

 changes may possibly be due to cell-inanition as a common un- 

 derlying factor. 



The parathyroid glands appear to be relatively larger in the 

 female. They apparently belong to that group of organs in 

 which growth persists in young rats, even when held at main- 

 tenance (constant body weight) by underfeeding. In adult rats 

 during acute and chronic inanition, the reduction in the size of 

 the parathyroids is nearly proportional to that of the body as a 

 whole. 



In histological structure, the parathyroid gland is relatively 

 more resistant than the thyroid to inanition. The changes in 

 the structure of the epithelial cells are somewhat similar to those 

 described for the thyroid, though in general less marked. In 

 many of the cells there is apparently no decrease in the average 

 size, but some (especially those degenerated) show marked 

 shrinkage. The nuclei may remain nearly normal in size and 

 structure, though usually exhibiting various stages of (rarely) 

 karyolysis or (more frequently) karyopycnosis. No cell-divi- 

 sion is found. The cytoplasm may be either somewhat reduced 

 in amount, sometimes deeply-staining ('oxyphile'), or may re- 

 main nearly normal in volume, with marked vacuolization 

 ('hydropic degeneration'). The stroma may remain normal in 



