Demonstration of Muscle Sphincters as a Capillary Component in the Human Heart
The capillary network in the ventricular myocardium in man consists of 2 sphincter-type capillaries (the metarteriole and the precapillary) and a nonmuscular capillary, the classic or true capillary. The muscular components of the metarterioles and of the precapillaries are innervated by nerve fibers of which the terminal structure ends as a knotted fibrillar process near the muscle nucleus. The sphincter capillary and its nerve constitute a functional unit. These structures are encountered in the myocardium of man more frequently than elsewhere. In man these functional units conceivably may play a much more prominent role than heretofore realized in the dynamics of cardiac vascularization.
- © 1959 American Heart Association, Inc.