Myoendothelial contacts in glomerular arterioles and in renal interlobular arteries of rat, mouse and Tupaia belangeri.

Cell contacts between elements of the tunica media and the intima in the afferent and efferent glomerular arteriole and in the interlobular artery were studied and evaluated semiquantitatively in thin sections of rat and mouse kidney. In the afferent arterioles, including their juxtaglomerular portion, contacts were seen between endothelial and smooth muscle cells, and between endothelial and granulated (renin producing) cells. The form of these musculo-endothelial contacts varied from simple appositions of perikarya and cell processes to extensive club-shaped indentations of endothelial cells into media cells (common) or media cells into endothelial cells (rare). Most of these cell contacts seem to contain myoendothelial gap junctions. Fewer, mostly club-shaped myoendothelial contacts were found in the interlobular arteries of rats and mice than in their afferent arterioles. Simple membrane appositions predominated among the numerous myoendothelial contacts of efferent arterioles. Similar results (without quantitative analysis) were obtained in the kidney of Tupaia belangeri. The myoendothelial contacts may allow the detection and propagation of mechanical (autoregulatory) and humoral stimuli.