[Structure of the dermal lymph capillaries and their functional interpretation].

The structure and function of the dermal lymphatics are described. The lymphatic system is considered to be an important part of the dermal microvascularisation. The characteristic ultrastructural features of the lymphatics were studied by electron microscopy. The lymphatic endothelial walls are closely connected with the connective tissue (interrupted basal lamina, lack of pericytes, elastic lamina and muscle cells), which makes possible the direct transmission of the pressure changes of the interstitial space to the initial lymphatics. The capillaries can change their dilatation rate due to the loose connection of the endothelial cells. The capillaries work like a piston. The valves (inlet and intralymphatic valves) ensure the centripetal lymph flow. It is assumed that the valves can change their form and position and that the intralymphatic valves (unicellular- and bunch valves) are rebuilt in order to fulfill the new requirements of the pressure variations. These valves help to direct the lymph flow. If the valve system is partially or completely insufficient, dermal lymph edema can develop.