ABSTRACT
The lipid lamellae of the intercellular spaces of the stratum corneum (SC) are essential components of an adequate barrier function [1-3]. In combination with the hydrolipidic layer-a water and oil mixture thought to cover part of the body surface-the barrier lipids (i.e., ceramides, cholesterol, and free fatty acids [FFAs]) prevent excessive transepidermal water loss (TEWL) and skin penetration of irritants and potentially harmful xenobiotics [4-6]. Because aged skin displays an increased susceptibility to irritants and the water retention capacity of surfactant-induced scaly skin is decreased, it has been hypothesized that changes in barrier lipid composition or their physical structure may account for these observations [7-11]. Furthermore, several skin disorders, such as atopic dermatitis [12-14], lamellar ichthyosis [15-17], severe xerosis [18,19], and psoriasis [20-23], most likely can be attributed to abnormalities of the intercellular lipids in the SC, which could be responsible for the functional disorders.
