THE PITUITARY BODY 



other than the thyroid are sources of antihormone and that 

 the neutrahzation of thyrotropic hormone does not occur in 

 the thyroid. After anterior pituitary extract had been in- 

 jected into rabbits for i months and the thyroid was then re- 

 fractory toward further treatment, the gland was removed 

 and, presumably still living, was perfused by the Carrel- 

 Lindbergh technic with normal serum containing anterior 

 pituitary extract. Thyroid-stimulating effects could be ob- 

 served within 24 hours. In other experiments the author was 

 surprised by the fact that a large volume of rabbit serum con- 

 taining antihormone only partially neutralized the thyro- 

 tropic action of anterior pituitary extract with which it was 

 mixed. The mixture was perfused through the isolated thy- 

 roid of the normal rabbit. 



Werner's experiments (1936) strongly support the view 

 that thyrotropic antihormone is an artifact characteristic of 

 relatively crude anterior pituitary extracts. Equivalent doses 

 (in terms of weight of crude gland) of extract of the beef 

 anterior pituitary were injected into guinea pigs and led to 

 the following conclusions: (i) whether or not antihormone is 

 produced depends on the type of extract not on its potency, 

 (2) it may be possible to produce antihormone by doses of ex- 

 tract without thyroid-stimulating effects, (3) the thyroids of 

 animals completely refractory to one extract may be readily 

 stimulated by the other — yet both were obtained from ox 

 pituitary — and (4) an extract may cause the formation of no 

 antihormone in the majority of animals even after injection 

 for nearly 3 months. As a basis for these conclusions the 

 author relied upon the basal metabolic rate and the histology 

 and total iodine-content of the thyroid. 



The assay of thyrotropic hormone. — Among mammals no 

 animal is as convenient for the assay of thyrotropic hormone 

 as the immature guinea pig. The histological signs of thyroid 

 stimulation — vacuolization of the colloid, hypertrophy, and 

 later, hyperplasia (increased mitotic division) of the epithe- 



[ 194] 



