528 



THYROIDECTOMY AND EARLY DEVELOPMENT 



RANA STAGE 17 



THYROID 

 HEART 



AMBYSTOMA' STAGE 31 



DISCUSSION: 



HEART 



THYRCMD ANLAGE 



Thyroidleaa tadpoles will not generally go through metamorphosis. This stage In 

 Eana piplens controls should he attained at ahout 75 days at lahoratory temperatures, pro- 

 viding the food, space, and other factors are adequate. There is no douht hut that the 

 pituitary gland is closely related to the thyroid in function. The active element of the 

 thyroid gland is iodine, and this may he administered in different forms (e.g., crystal- 

 line iodine, KI, or in thyroxin). Thyroldless emhryos stimulated hy thyroxin may occasion- 

 ally surpass the controls in metamorphic changes. 



IHFUN0I3ULUH 



X. ■ 



» JL 



ENDOCRINE ANLAGEN AT THE 

 5 mm. STAGE (FROG) 



RKJf'KHENCES : 



Allen, B. M., I918 - "The results of thyroid removal in the larvae of Bana pipiens." 



Jour. Exp. Zool. 2lt:i^99 (see ihid. 50:201). 

 Allen, B. M., I958 - "The endocrine control of amphibian metamorphosia. " Biol. Kev. 15:1. 

 Bauman, G., 1956 - "Modifications des premiers stades du developpement dea oeufa de ba- 



traclens anourea sans 1' Influence de la Thyroxine." C. B. Soc. de Biol. 121:1052. 

 Hoskine, E. E. & M. M. Hoskina, I919 - "Growth and development of Amphibia as affected by 



thyroidectomy." Jour. Exp. Zool. 29:1. 

 Larson, M. E., 192? - "The extirpation of the thyroid gland and Ita effecta upon the hypo- 



physia in Bufo amerlcanus and Bana pipiens." Sci. B^lll. Univ. Kansaa. 17:519' 

 Stokes, M., I9U0 - "Esrly localization of the thyroid anlage in %^la regllla." Proc. Soc. 



Exp. Biol. & Med. 1+5:681. 

 Taylor, A., 195'+ - "Athyroidism in the salamander, Trlturus toroaus." Jour. Exp. Zool. 



275:155. 



