Peter M. Elias, Kenneth R. Feingold

Introduction. Definitions and Broad Concepts. Integrative Aspects: Protective Functions of the Stratum Corneum. History Overview. More History: Evolution of the Barrier from Saran Wrap to Biosensor. Structure of the Statum Corneum. Lipid Composition. SC Ceramides. Morphology of the Stratum Corneum Barrier: Overview. Structure of the Stratum Corneum Lipid Membranes. Cornified Envelope and Corneocyte-Lipid Envelope. Filaggrin. Keratins. Corneodesmosomes. Tight Junctions and the Permeability Barrier. Comparative Aspects of Barrier in Other Squamous Epithelia. Barrier Function in Mucosal Epithelia. Dynamic Properties of the Stratum Corneum. Stratum Corneum pH: Origin, Functions, and Measurement of the acid Mantle. Lipid Processing: The Final Step in Barrier Formation. Desquamation. Regulation of Stratum Corneum Formation. The Epidermal Lamellar Body as a Multifunctional Secretory Organelle. Development of the Barrier in the Fetus. Regulation of Barrier Function by Calcium. Cytokines: The Two-Edged Sword. Nuclear Hormone Receptor 'Liposensors' Regulate Differentiation and Barrier Formation. Functions of the SC. Maintenance of Permeability Barrier Homeostasis. Defense from Mocrobial Invasion. The Epidermal Antioxidant Barrier. Sources and Role of SC Hydration. Metabolism of Foreign Substances: The Chemical Barrier. Vitamin D Formation and Function in Barrier. Functional Abnormalities of the SC. Diseases that Affect Barrier Function. Pathogenesis of Barrier Abnormalities in the Ichthyoses. Pathogenesis of Desquamation and Permeability Barrier. Environmental Occupational Disorders. The Aging Epidermal Barrier. Psychological Stress and the Psychosensory Interface. Atopic Dermatitis. Epiologue