Periodic acid methenamine silver (pam) staining of the human subcutaneous lymphatic vessel

The fine structure of the subcutaneous lymphatic vessel taken from the dorsum pedis of the human adult was investigated without and after impregnation by periodic acid methenamine silver (PAM). To check the stainability of another tissue, the renal glomerulus of the rat was also examined in the same way as outlined above. The membrane system of various cells stains positive. No special surface coat of the endothelial cell of the lymphatic vessel was detected. The fine intracellular filament as well as a continuous basal lamina of the endothelial cell were almost PAM-negative, although a part of the basal lamina was occasionally weakly positive. The chemical composition of the basal lamina of the lymphatic vessel is considered to differ from that of the glomerular blood capillary of the kidney, which is PAM-positive. This difference is thought to be due to the smaller polysaccharide content in the former than in the latter.