THE PITUITARY BODY 



transplants were not free from nervous tissue.) Similar ex- 

 periments in Amblystoma punctatum were unsuccessful.^ 



Atwell (1937) found that compensatory hypertrophy of 

 thyroid fragments in larvae of R. pipie?js is prevented by 

 hypophysectomy. This finding is in accord with other work 

 in amphibia and mammals. 



x^nother group of authors has published observations 

 largely confirming and extending previously reported experi- 

 ments in urodele amphibia. Uhlenhuth and his collabora- 

 tors^ again described the stimulating effect of anterior pitui- 

 tary extract on the thyroid as indicated by morphological 

 changes in the latter, by increased oxygen-consumption or 

 by precocious metamorphosis. Most of their observations 

 were made in Amblystoma tigrinum. The photomicrographs 

 of Figure 11 are reproduced from those published by Adams 

 and Martindale (1936). The injection of an alkaline extract 

 of the pars glandularis of the ox ("Phyone") produced a 

 marked stimulation of thyroid function in hypophysecto- 

 mized newts {Triturus viridescens). Maximum changes were 

 produced after daily injections had been given for about three 

 weeks. The thyroid underwent regression to its former con- 

 dition, characteristic of hypophysectomy, only weeks after 

 injections were stopped. 



Hypophysectomy prevents molting in adult urodele am- 

 phibia and, in this respect, resembles thyroidectomy. The 

 cornified cells of the epidermis are retained as successive 

 layers. These effects of extirpation of the pituitary do not 

 occur in larval urodeles or in neotenous forms, except per- 

 haps in Necturus maculosus (Osborn, 1936). Adams and Gray 

 (1936) were able to cause molting of the layers of cornified 

 epidermis of hypophysectomized newts {T. viridescens) by 

 the administration of anterior pituitary extract, thyroxine, or 



2 Blount's results in Amblystoma indicated that the pars neuralis is required for 

 the differentiation of the pars glandularis. In his animals there also were a pro- 

 nounced intensification of pigmentation and distortions of growth. 



3 Uhlenhuth and Schwartzbach (1935); Uhlenhuth, Schwartzbach, and Thomp- 

 son (1935); and Schwartzbach and Uhlenhuth (1936). 



[176] 



