Ultrastructural demonstration of anionic sites in basement membrane zone by cationic probes.

Anionic sites were demonstrated ultrastructurally in both the dermal and epidermal edges of the lamina densa using strongly cationized polyethyleneimine as a tracer. Enzyme digestion with heparitinase and pronase removed the anionic binding sites, indicating that the sites consisted largely of heparan sulfate proteoglycan.