[Structural picture and mechanism of action of the "initial lymph system"]

The general structural features of the initial lymphatics are exhibited in the view of light and electron microscopic findings. Special attention was given to recent results in scanning electron microscopy. As regards the terminology of the initial lymphatic structures, it is suggested that the term "initial lymphatic sinuses be used" instead of "initiale Lymphbahn" designated a functional unit consisting of the initial lymphatic sinuses including the prelymphatic interstices and precollecting vessels. In addition to the functional hypotheses, so far made for the mechanism of action of the initial lymphatics, a further aspect is considered based on the active cooperation of the vessels in lymph formation evoked by the contractile properties of the lymphatic endothelium.