Epidermal Lipids and Formation of the Barrier of the Skin

The evolution of life in the relatively dry terrestrial environment required the development of a waterproof integument.1 In the terrestrial vertebrates, the stratum corneum provides the primary barrier to water loss. The barrier function of the stratum corneum depends upon a unique mixture of lipids that form lamellar structures in the intercellular spaces.2-5 This generally consists of ceramides, cholesterol, and long chain fatty acids.