344 C. M. JACKSON 



The interstitial tissue or stroma of the parathyroid rarely 

 shows any noteworthy changes. In some cases it appears 

 slightly increased in amount, with edemic appearance, but not 

 so often as in the thyroid. 



c. Structure of parathyroid in adult rats after acute and chronic 



inanition 



In adult rats subjected to acute or chronic inanition, the di- 

 mensions of the parathyroid gland are given in table 1. While 

 it is impossible to draw any final conclusion, on account of indi- 

 vidual variation and the small number of observations, there 

 seems to be a decrease in the size of the parathyroid as a result 

 of inanition. When the average diameters and corresponding 

 (final) body-weights are plotted graphically, the parathyroids 

 appear approximately normal. Their decrease during inanition 

 therefore would appear to be nearly proportional to that of the 

 whole body. 



In histological structure, the parathyroids in adult rats after 

 acute and chronic inanition show changes essentially like those 

 described for the younger maintenance rats. The changes are 

 in general less marked than in the thyroid, but there is consid- 

 erable individual variation. Although there is cell-shrinkage in 

 some places, especially where degeneration is marked, in other 

 places there appears no decrease in the average size of the para- 

 thyroid cells. 



The cytoplasm in adult parathyroids following inanition some- 

 times appears nearly normal, but usually shows typical vacuoli- 

 zation (^hydropic degeneration'), or in some cases a more deeply- 

 staining homogeneous or coarsely granular structure (especially 

 accompanying markedly pycnotic nuclei). 



The nuclei may be nearly normal, but usually show hyper- 

 chromatic changes (more rarely hypochromatic), being usually 

 found in the earlier (rarely later) stages of karyopycnosis. These 

 changes occur not merely in restricted areas, or near the free 

 surface (as found in the normal gland) but usually and typically 

 involve large areas and frequently the entire gland. Thus while 



