THE PITUITARY AND THE THYROID 



lobe extract. The administration of an anterior-lobe extract 

 to a susceptible animal like the young guinea pig produced 

 the striking results given diagrammatically in Figure 49 

 (data of Closs, Loeb, and MacKay). It is evident that the 

 anterior-lobe extract caused a hypertrophy of the thyroid 

 with a reduction in both the concentration and total amount 

 of iodine present. The marked increase in blood iodine was 

 practically entirely due to an increase in the alcohol-insoluble 



□ 



AUCOHOL-SOLUBUE 

 FRACTION 



ALCOHOL-INSOLUBLE 

 FRACTION 



Fig. 49. — The effect of anterior-pituitary extract on the weight of the thyroid 

 and on the amount and distribution of iodine in the thyroid and blood of the guinea 

 pig. Adapted from Experiment 2 of Closs, Loeb, and MacKay (1932). 



(thyroid hormone) fraction. Foster, Gutman, and Gutman 

 showed that the reduction in the total iodine of the thyroids 

 of sheep treated with anterior pituitary extract was due to a 

 reduction of thyroxin and organic iodine, whereas the inor- 

 ganic iodine was scarcely affected. 



Any increase in basal metabolism as a result of the adminis- 

 tration of anterior pituitary implants or extracts appears to 

 depend upon the stimulation of the thyroid. Benedict and 

 Homans (four dogs, only one reported as completely hypo- 



[267] 



