Histological demonstration of initial lymphatics in human skin: comparison between different extension techniques.

Initial lymphatic vessels (IL) are difficult to demonstrate histologically in excised normal skin, as they are usually completely collapsed. In this report three different methods (vacuum extension, large traction extension, and small traction extension) are described by which human skin specimens can be mechanically extended. After extension specimens were Epon enbedded and the IL counted and their diameters measured. The greatest number of lymphatic vessels was found in specimens extended by vacuum, and the smallest number in small specimens extended by traction. The highest density of lymphatic vessels was found 50-300 microns below the epidermis. Our data reveal that vacuum extension is useful for investigating questions concerning the topography of IL, whereas preparations extended by traction are more suitable for obtaining information about single lymphatic vessels.