The epidermal helix: a model for the bilayer couple phenomenon.

Narrow strips of isolated epidermis rapidly assume a helical conformation when placed in a dilute hypotonic aqueous solution of histamine as a free base. The same belical formations could be induced by dilute hypotonic solutions of alkalis or acids. This coiling resulted from damage to the malpighian cells, with consequent asymmetric osmotic swelling of the epidermis, thus producing torsional forces on the stratum corneum. In essence, the epidermal helix proved to be a pH dependent, osmotically induced, bilayer couple phenomenon.