THE ROLE OF THE FETAL ENDOCRINE GLANDS IN DEVELOPMENT*

Abstract

The author directs attention to the question of whether the developing endocrine glands contribute to the processes of embryonic growth, development or differentiation in a material way. Basic problems include the time in development at which these glands attain the capacity to secrete hormonal substances, and the evidence for a release of hormones into the organism, as well as the capability of organs and tissues within the body to respond to such activating substances. The evidence for functional activity on the part of the pituitary and thyroid glands in metamorphosis in amphibia is very definite but that these, or other, endocrine organs play a role in embryonic development in higher vertebrates (birds and mammals) is less satisfactorily demonstrated. Consideration is given to the available evidence for function on the part of the pituitary, thyroids, adrenals, gonads, and to a lesser extent the pancreas. The literature bearing on the problems, the technics employed in investigation, and some of the divergent opinons as to the interpretation of observations are discussed.