THE INFLUENCE OF DIET AND IODIDES ON THE 



HYPERPLASIA OF THE THYROID GLAND 



OF OPOSSUMS IN a\PTIVITY 



R. R. BENSLEY 



■From the Hull Labordtartj of Anatomij_ University of Chicago 



In a recent paper on thyroid gland of the opossum ('14) I 

 showed that, when these animals are brought under domestica- 

 tion, the thyroid gland undergoes a prompt and characteristic 

 change, marked by hyperplasia of high degree, by disappear- 

 ance of the stored colloid and of the intracellular crystals, and 

 by the appearance in the free ends of the epithelial cells of 

 granules which I interpreted as a new secretion antecedent. I 

 showed also that this reaction was not a seasonal variation asso- 

 ciated with hibernation, since animals captured at intervals 

 throughout the winter months presented always a normal type of 

 gland structure, while those kept for a few weeks in the labora- 

 tory, had hyperplastic glands. In one animal kept until June 

 1, also, there was no indication of spontaneous reversion as 

 might be expected if the changes were associated with hiberna- 

 tion. On the contrary, reversion to a colloid type, as in Marine's 

 experiments, was accomplished by the administration of iodine. 



Since the reaction in question was obviously the result of new 

 conditions incident to the confinement of the animals under 

 laboratory conditions, it was apparent that the means for the 

 control of this hyperplasia would also be available, if the factors 

 operative in producing it could be discovered. Accordingly, I 

 have devoted the animals which I have been able to secure this 

 year to an attempt to determine the relations of iodine adminis- 

 tration, and of dietary, to the changes described. While other 

 factors, as, for example, injuries incident to capture, infections 

 following such injuries, lack of exercise, mental conditions in 

 captivity, and pathogenic organisms might conceivably be pri- 



THE AMKKIC^VN JOURNAL OK ANATOMY, VOL. 19, NO. 1 



