INANITION OF THYROID IN RATS , 347 



mals) two types of cells: (1) 'principal' cells described by Welsh 

 as having in man "a, relatively small and clear protoplasmic 

 body, and a relatively large and clear nucleus." These cells 

 constitute the chief part of the gland, and are constantly present. 

 (2) The 'oxyphile' cells usually have relatively more cytoplasm, 

 finely granular and sometimes finely vacuolized. The nucleus is 

 both relatively and absolutely smaller than in the 'principal' 

 cells, its outline more circular and chromatin more dense, ''so 

 that no nuclear network can be detected and the entire nuclear 

 mass appears uniformly and deeply stained." These 'oxyphile' 

 cells are found by Welsh in a very large proportion of cases, 

 though not all, and never so abundantly as the 'principal' cells. 

 They never form a large proportion of the gland, and may occur 

 as small masses (often just beneath the capsule) or as scattered 

 cells throughout the gland. 



The presence of these 'oxyphile' cells has been confirmed in 

 man and a part (not all) of the lower animals. They are gen- 

 erally considered to represent cells in functional activity. Against 

 this view, however, is the fact that they are quite variable in 

 appearance, and frequently absent altogether (sometimes in 

 man; constantly in some of the lower animals, and especially in 

 the young). 



Although I have made no special study of the parathyroid in 

 any other form, the conditions found in the rat lead me to sug- 

 gest the possibility that these 'oxyphile' cells may represent 

 merely atrophic types, with no functional significance. It will 

 be noted that (although the cytoplasm is relatively abundant) 

 the nucleus of these 'oxyphile' cells as described by Welsh and 

 others corresponds closely with the pycnotic condition charac- 

 teristic of atrophic, degenerated cells, such as are described above 

 in the normal parathyroid and thyroid glands, and are increased 

 in number during inanition. While the evidence at hand is in- 

 sufficient for a final conclusion, it seems to me that this interpre- 

 tation is a possibility which should be kept in mind during further 

 investigation of the matter. 



