THE CAROTID BODY: A PATHOLOGIST'S VIEW.

A review of the literature on the histogenesis and function of the carotid body suggests that the results and the original interpretations of embryological, histological and histochemical investigations have not provided a convincing explanation of the origin of this structure. That the carotid body is developed from mesoderm and is a sensory organ (chemoreceptor) seems unlikely because of: morphological similarities between some of the carotid body tumours and certain tumours of peripheral nerves; certain electron microscopic similarities between the cells of carotid body and adrenal medulla; chromatographic demonstration of catecholamines in the human carotid bodies; and contradictory results of both animal experiments and clinical observations concerning function of this structure.It is concluded that the carotid body arises from ectoderm and should probably be classified as a gland of internal secretion, related to the adrenal medulla and other paraganglia.