title: Hypothesis: the epidermal permeability barrier is a porous medium.
abstract: The stratum corneum is a complex biological material characterized by very low permeability to water and most other molecules. This material may be thought of as a 'porous medium' composed of impermeable and permeable regions. Intercellular lipid membranes in the stratum corneum are postulated to exist in a mixture of two phases: solid (i.e. impermeable) and liquid crystalline (permeable). The corneocyte envelope is classified as impermeable. Diffusion mechanisms of solutes within, across and between the intercellular lamellae are discussed. This model represents a refinement of previous theories about the physical structures responsible for the low observed permeability of the stratum corneum.
authors.affiliation: Dept. of Medicine, University of British Columbia, Vancouver, Canada. nkitson@interchange.ubc.ca
authors.forename: N
authors.initials: N
authors.lastname: Kitson
authors.forename: J L
authors.initials: JL
authors.lastname: Thewalt
mesh_terms: D004058:Diffusion; D000078404:Epidermal Cells; D004817:Epidermis / Q000033:anatomy & histology / Q000378:metabolism*; D005110:Extracellular Space / Q000378:metabolism; D006801:Humans; D050356:Lipid Metabolism; D008055:Lipids / Q000737:chemistry; D010539:Permeability; D016062:Porosity; D013329:Structure-Activity Relationship; D014867:Water / Q000378:metabolism
chemical_list: D008055:Lipids; D014867:Water