ABSTRACT
In skin, mucous membranes, and solid organs, the lymphatic network comprises a superficial and a deep system from which the lymph is drained by precollector channels that continue centrally into collecting vessels. The lymphatic vessels to some extent resemble blood vessels. Two basic functions exerted by the lymphatics prevail: one is the uptake of tissue fluid as a process of lymph formation by the vascular structures at the beginning of the lymphatic system. The high phagocytotic activity of the lymphatic endothelium in the initial area of the lymphatic vascular system could be demonstrated in fixed tissue specimens. With the aid of the Scanning Electron Microscopy mainly the second component of the basement membrane can be visualized in initial lymphatics. An incontinuous elastic membrane between that layer and the tunica media composed of fine elastic fibers appears only in the largest lymphatics.
