The Morphology and Physiology of the Salamander Thyroid Gland

Abstract

ABSTRACT In the study of the physiology of the thyroid gland it is becoming more and more evident that the function of this organ is composed of a number of component activities. Only some of them are controlled by intrinsic mechanisms, while the most important of them, the release of the active secretion product of the gland from the follicles into the blood circulation is effected by stimulation through an extrinsic “releasing mechanism.” In warm-blooded animals the study of this releasing mechanism has received considerable attention, and although the question cannot by any means be considered a closed chapter of thyroid physiology, the work of O. A. Andersson(1), Leo Asher(2), Cannon and Fitz(3), L. B. Wilson(o) and others, is generally credited with having demonstrated that the autonomous nervous system is the path over which the stimuli of the releasing mechanism reach the thyroid in warm-blooded animals. The senior author of this paper has been interested, for some time, in the physiology of the thyroid of cold-blooded animals, and especially in that aspect of it which concerns the nature of the releasing mechanism. This work has now entered an advanced stage and certain definite conclusions are possible. Although the results, together with the records, will be published in a series of more extensive articles, it seems desirable that the chief results be made accessible at once.