Endothelial cell helix in small arterioles of human ureters. A study by scanning electron microscopy (SEM)

Microvessel corrosion casts of human ureters were prepared. Portions of casts were longitudinally cut by use of a pulsed Eximer laser beam in order to get insight into microvessel branches studied in SEM. Larger arterioles (greater than 30 microns in diameter) showed oval imprints of endothelial cell nuclei along the vessel axis. Imprints were found in furrows parallel to resin ridges. Smaller arterioles (less than microns in diameter) displayed imprints of nuclei aligned in a helix around the vessel axis. With regard to capillaries, one nucleus imprint was spaced far apart from the other. Venules demonstrated a reticular network of thick, attenuated resin ridges and of small meshes which consisted of round or oval nucleus imprints. It is concluded that smaller arterioles form an endothelial cells helix.