Mammalian Epidermal Barrier Layer Lipids: Composition and Influence on Structure

摘要: The outer layers of the mammalian epidermis protect organism from water loss and external injury. bather as visualized with tracers has been shown to develop initially in stratum granulosum concurrent intercellular deposition extruded lamellar-body contents. This lamellar material greatly expands compartment, following cornification appears form broad sheets which freeze fracture like lipids, deviating fracture-plane hydrophobic interior membrane apparently more space. Isolated upper epidermal were first obtained neonatal mice staphylococcal exfoliatin, then treated lipid solvents order both identify structures formerly obscured by characterize lipids contributing barrier function. Histochemical stains also used localize phospholipid neutral deposits layers. After solvent treatment, plane reverted space plasma membrane, revealing sparse particles low corneum particle-free faces mid-to-upper regions. Extracted contained 3-4% lipid, almost equally distributed between polar nonpolar substances, unexpectedly large quantities glycolipid, hydrocarbons, free fatty acids. Gas liquid chromatography demonstrated unusually long-chain acids (C24:0 C26:0) all fractions spaces, phospholipids within granular cells, PAS-positive cells. These combined histochemical biochemical studies confirm earlier reports demonstrating a shift during cornification. They indicate that are segregated pattern consistent electron microscopic images. Furthermore, they suggest layer through yet undefined mechanisms, may be transformed into cornified layer. Finally, observed admixture long-chain, highly saturated acid chains, well sterols ideally suited (and situated) function permeability barrier.