[Biophysical characterization of the stratum corneum. Relationship between structure and properties].

Studies carried out over the last ten years have determined the structure and chemical composition of the stratum corneum and their significance for biologic function; the stratum corneum (SC) is composed of flat layers linked to each other by desmosome plates. Intercellular spaces are composed mainly of double lipid layers which are responsible for the main part of the barrier function of the SC. This barrier between the body and the environment must be effective despite the deformations and various insults (chemical, physicochemical) to which the SC is subjected. The SC fulfills its barrier function through remarkable physical properties of which most originate in an ability to bind water molecules to protein sites whose presence depends on the humidity of the environment in which the SC was produced. Lastly, the SC exhibits some enzyme activities and consequently can no longer be considered as an inert membrane.