An ultrastructural study of the vascular alterations within the carotid bodies of spontaneously hypertensive rats (SHR).

Electron microscopic studies of the fine structural changes of the arterioles within the carotid bodies of spontaneously hypertensive rats (SHR) in the established phase of hypertension revealed partly hyperplastic endothelial cells. In the subendothelial space a multiplication of the basal laminae was observed often of a whirl-like shape. The smooth muscle cells of the media were hypertrophied, bizarre and with numerous projections. They exhibited a marked increase in cell organelles. The extracellular space was extensively enlarged and partly vacuolated. It contained a basement membrane-like material which was connected with the basal laminae of the myocytes. All these alterations produced a pad-like thickening of the arteriolar wall which narrowed the vessel lumen. These findings and their possible effects on carotid body function are discussed.