Percutaneous absorption and the surface area of occluded skin.

Scanning electron microscopy of samples of human skin occluded for 72 h, revealed that the hydrated stratum corneum not only swells, but develops multiple folds. Surface area estimations of such stratum corneum, utilizing stereo pairs of the photomicrographs, indicated a 37% increase over the normal, non‐occluded horny layer values. It is speculated that the increase in absorptive area contributes to the increased skin permeability following occlusion.