INANITION OF THYROID IN HATS 331 



unusual amount of normal variability in histological structure, 

 doubtless due at least in part to functional stages which are as 

 yet imperfectly understood. Furthermore, on account of the 

 extreme sensitiveness of the thyroid, it reacts strongly to vari- 

 ous influences by changes which lie on the border-line between 

 normal and pathological. So-called degenerative conditions 

 (desquamation and degeneration of epithelium) appear to a 

 limited extent even in the thyroids of normal animals (including 

 man), although these conditions probably have no physiological 

 significance. Under various abnormal conditions, these retro- 

 gressive changes appear to be increased in extent and intensity. 

 ' Having reviewed the variable structure of the thyroid, we ma}' 

 now consider briefly the specific effects of inanition, as found by 

 the few investigators who have studied the histological changes. 



Barbera ('02) studied the effects of acute inanition ui^on the 

 thyroid gland in 3 rabbits and 1 dog, with controls of the same 

 sex and from the same mother. The rabbits were starved 7 to 

 11 days, and the dog 21 days, with loss of about 30 per cent in 

 lK)dy weight in each case. No data are given as to weight of 

 the gland. No measurements of the entire cells are stated, but 

 they were found reduced in size, the loss in the cytoplasm being 

 greater than in the nucleus. The average of a large number of 

 measurements of the nuclear diameters showed in the rabbit 5.73 

 X 4.99 micra in the controls, and 5.75 X 3.84 in the starved ani- 

 nals. This would indicate a reduction in size with relative elon- 

 gation of the nuclei. This elongation of the nucleus was not 

 found in the dog, however, where the average of 5.11 X 4.62 

 micra in the controls was reduced to 4.44 X 4.28 micra in the 

 starved. The intercellular substance was also found reduced in 

 amount, but colloid formation a})peared to continue normally 

 (hence no sym]3toms of hypothyroidism). 



As above stated, I have likewise found in the rat thyroid dur- 

 ing inanition a slight reduction in the size of the nucleus, which 

 is usually much less marked than the decrease in cytoplasm. I 

 find the sha])e of the nucleus dependent upon the form of the 

 cell; in cases where the cell becomes flattened, the nucleus be- 

 comes correspondingly elongated, l)ut otherwise it usually i"e- 



