Quantitative investigation on the anterior pituitary-thyroid mechanism during frog metamorphosis.

Abstract

IN A large number of previous investigations it has been definitely proved that in amphibians metamorphosis is dependent upon the normal functioning of the anterior pituitary-thyroid system (with regard to the extensive literature, see 1, 2). Little is known, however, regarding the variations in thyroid function during metamorphcsis and the corresponding changes in the thyrotropic activity of the anterior pituitary, and the statement commonly found in textbooks that thyroid activity increases during metamorphosis is based chiefly on morphological studies. Furthermore, the time relations between the supposed functional variations and between these and the various stages of metamorphosis have been subjected to little investigation. For this reason an attempt has been made to study the functional variations possibly occurring in the anterior pituitary-thyroid system during the various stages of metamorphosis using a quantitative method. The species used in this investigation was the South African clawed toad...