INANITION OP^ THYROID IN RATS 345 



no new types of cells occur, the atrophic types which occur in- 

 frequently and in small amount in the normal gland become 

 very frequent and extensive during inanition. The changes in 

 general appear to be somewhat more marked and extensive dur- 

 ing chronic than during acute inanition, although there are indi- 

 vidual variations. 



The interstitial connective tissue or stroma of the parathyroid 

 appears usually somewhat more distinct, and often relatively in- 

 creased slightly in amount, during acute and chronic inanition 

 of adults. 



d. Discussion and conclusions 



Broadly speaking, we may conclude from the foregoing that 

 in general the effects of inanition upon the parathyroid gland 

 are similar to those on the thyroid, but somewhat less marked. 

 The similarities and differences include the following. 



The parathyroid gland apparently belongs to that group of 

 organs which in young rats tend to continue growth, even when 

 the body-weight is held constant. This group includes the eye- 

 balls, spinal cord, testes, skeleton, alimentary canal, suprarenal 

 glands and hypophysis. The thyroid, on the contrary, belongs 

 to the group losing weight (Jackson '15 b). 



In the parathyroid, many of the individual cells apparently 

 do not decrease in size during inanition; whereas in the thyroid 

 the decrease is usually well marked, especially in the cytoplasm. 



In both parathyroid and thyroid glands, the cytoplasm usu- 

 ally shows marked changes during inanition, whether or not it 

 is decreased in amount. Vacuohzation ('hydropic degenera- 

 tion') is most frequent, but deeply-staining, eosinophile conden- 

 sations of homogeneous (especially in the thyroid) or coarsely 

 granular (especially in the parathyroid) types may occur. 



The nucleus in both parathyroid and thyroid glands during 

 inanition tends to become hyperchromatic (more rarely hypo- 

 chromatic). Thus the nuclei are commonly found in various 

 stages of pycnosis, the earlier stages being typical in the parathy- 

 roid, while in the thyroid the later stages (and even karyor- 

 rhexis) may frequently occur. 



