The carotid body role in oxygen sensing: Anatomy, neurovascular organization, and structural bases of chemotransduction.

Abstract

Background: The carotid body is a small, highly vascularized organ located at the bifurcation of the common carotid artery and serves as the primary peripheral detector of arterial oxygen tension in mammals. Although its physiological role in ventilatory and autonomic reflexes has been extensively investigated, these functions are fundamentally dependent on its specialized anatomical organization. Objective: This review provides a comprehensive overview of the anatomical organization of the carotid body, highlighting how its gross morphology, microvascular architecture, cellular composition, and innervation support rapid oxygen sensing and chemosensory signal transmission.

Methods: Current evidence from anatomical, histological, ultrastructural, developmental, comparative, and experimental studies was critically reviewed to summarize the structural organization of the carotid body across mammalian species. Particular emphasis was placed on the relationships between vascular organization, cellular arrangement, and neural connectivity, as well as structural adaptations associated with chronic hypoxia and disease.

Results: The carotid body is characterized by an exceptionally dense capillary network, intimate neurovascular coupling, and glomerular clusters composed of excitable type-1 (glomus) cells surrounded by supportive type-2 (sustentacular) cells. These structural features facilitate efficient oxygen delivery, rapid detection of changes in arterial oxygen tension, and effective transmission of chemosensory information to the central nervous system. Comparative and developmental studies further demonstrate species-specific anatomical differences and substantial structural plasticity in response to chronic hypoxia, aging, and pathological conditions.

Conclusions: The specialized anatomy of the carotid body forms the structural basis of its remarkable sensitivity to changes in arterial oxygen tension. Integrating current knowledge of its vascular, cellular, and neural organization provides important insight into peripheral chemoreception and establishes an anatomical framework for understanding carotid body dysfunction in cardiopulmonary and metabolic diseases.