[Cutaneous lipids: from physiology to the clinical].

The primary function of the epidermis is to produce the waterimpermeable stratum corneum that permits terrestrial life. Extracellular glycosylceramides are the main precursors of the stratum corneum ceramides which play a role in the cohesion of corneocytes and the establishment of the barrier function. The physiological desquamative process depends upon the transformation of glycosylceramides to ceramides and of cholesterol sulfate to cholesterol. Intracellular ceramides participate to the terminal differentiation process of the epidermis. Abnormalities in the synthesis and/or the secretory mechanisms of the epidermal lipids induce various skin disorders. Such diseases may have a genetic background or result from the influence of environmental factors.