The extension technique: a new method of demonstrating initial lymph vessels in excised human skin.

The initial lymph vessels, the lymph capillaries and precollectors, are difficult to detect in normal skin using routine histological methods. A method is described in which specimens of the skin are fixed in an expanded condition. In 1.05 microns thick plastic-embedded sections the dilated lymph vessels of the skin can be demonstrated. The dermal lymph vessel network can be seen following the subepidermal injection of a coloured solution. The endothelial cells and subendothelial fibrous network can be examined using electron microscopy.