ABSTRACT
The skin is not a uniform surface. The surface area of the exposed skin is increased by approximately 30% by the fine wrinkles as compared with a flat surface. A mature human weighing 65 kg will have approximately 18,000 cm2 of skin surface area. The properties of the skin vary according to the anatomical locations. Current understanding of the formation of the stratum corneum comes from studies of the epidermal responses to perturbation of the skin barrier. There are several experimental procedures to disrupt the skin barrier: extraction of skin lipids with apolar solvents, physical stripping of the stratum corneum using adhesive tape, and chemically or physically induced irritation. Several lines of evidence indicate that the skin barrier lies within the stratum corneum. Perhaps the most convincing proof is provided by the demonstration that physically stripping off the outermost layers of the skin results in a dramatic increase in the permeability to water and other compounds.
