Characterization of epidermal glycosaminoglycans synthesized in organ culture.

1. Cellulose acetate electrophoresis together with specific enzymic and chemical degradation procedures indicated that hyaluronic acid (83%) and heparan sulphate (14%) were the major glycosaminoglycans synthesized by the epidermis when pig ear skin slices were cultured in the presence of D-[3H]-glucosamine and 35SO4 2-. 81% and 50%, respectively, of the total amount of each epidermal glycosaminoglycan was extracellular. 2. Total epidermal glycosaminoglycan synthesis decreased by 50% after 5 days in culture. 3. When the epidermis was cultured in the absence of the dermis the synthesis of hyaluronic acid was considerably reduced. The synthesis of sulphated glycosaminoglycans was essentially unaffected by the absence of the dermis. 4. 10(-5) M all-trans-retinoic acid stimulated the synthesis of hyaluronic acid and, to a lesser extent, of sulphated glycosaminoglycans whether the dermis was absent or present during culture. 5. The results suggest that hyaluronic acid may play an important role in some aspects of epidermal differentiation.