EPIDERMAL BARRIER FUNCTION - INTERCELLULAR LAMELLAR LIPID STRUCTURES, ORIGIN, COMPOSITION AND METABOLISM

In this short review, I have described recent advances in our understanding of mammalian stratum corneum. New ultrastructural methods complement powerful physical-chemical methods, together providing precise information about the structure and molecular architecture of stratum corneum intercellular domains. Secretion of epidermal lamellar body contents, not only of lipid precursors, but also of hydrolytic enzymes, results in dynamic modulations within the stratum corneum interstices; i.e., this tissue can no longer be considered inert. Furthermore, the epidermis is now appreciated to be a lipid biosynthetic factory, with all of the nucleated layers participating actively. Finally, though largely independent of the regulatory influence of circulating lipids, epidermal lipid synthesis is regulated by barrier requirements, and transepidermal water loss appears to be a regulatory factor.