Chromaffin Tissue and Paraganglia

Abstract

The status of the so-called abdominal chromafiin tissue is rather clearly defined. It is generally accepted as being true chromaffin tissue, with the ability to secrete epinephrine. Although the concept of the nervous origin of the adrenal medulla has been bitterly contested by a few workers, it is on the whole generally conceded, and the argument seems equally strong for a similar origin of the extra-adrenal chromaffin tissue. These two tissues seem to be similar both in origin and in function, and to correspond to the original meaning of the word paraganglion. The carotid and cardio-aortic bodies are non-chromaffin in nature, and apparently represent, as Nonidez (''37a, p. 311) says, "Complex neurovascular structures intimately associated with the branchial arches of the embryo." They are presumably sensory in function, probably representing receptors sensitive to chemical changes in the blood, through which vascular and respiratory reflexes are initiated. Their neurogenic origin has not been proven, and the propriety of terming them paraganglia may well be questioned.