Electron microscopic observations of stratum corneum intercellular lipids in normal and atopic dogs

The barrier function of mammalian skin is maintained by intercellular strat um corneum lipids. In human patients with atopic dermatitis, an abnormal li pid barrier results in dry skin and increased transepidermal water loss. At this time, it is not known if a defective lipid barrier is present in atop ic doors. Normal and atopic canine skin were postfixed in ruthenium tetroxi de and studied using transmission electron microscopy to determine structur al differences within stratum corneum lipids. Intercellular lipid lamellae were graded on a semiquantitative scale. The deposition of stratum corneum. lipid lamellae in atopic canine skin appeared markedly heterogeneous compa red with that seen in normal canine skin. When present, the lamellae often exhibited an abnormal structure. The continuity and thickness of the interc ellular lipid lamellae were significantly less in nonlesional atopic than i n normal canine skin. These preliminary observations suggest that the epide rmal lipid barrier is defective in atopic canine skin. Additional studies a re needed to further characterize the biochemical defect and to possibly co rrect it with nutritional and/or pharmacologic intervention.