Lymphatics of the Mitral Valve of the Dog

Abstract

Thin-walled vessels have been visualized histologically in the mitral valve of the dog; these vessels were increased in number and caliber in animals with chronic impairment of cardiac lymph flow. Injection of diluted India ink into the free edge of the anterior mitral leaflet of the beating heart revealed extensive networks of vessels, grossly visible on the atrial surface of the valve. Histological study showed the India ink to be within thin-walled channels. Thus, there is compelling evidence that the visualized vessels are lymphatics and that their size and number increase when the cardiac lymphatic drainage is chronically impaired. The possible significance of the presence of lymphatic capillaries in the mitral valve is discussed.