Clinical Evaluation and Instrumental Techniques in Dermatology

Stratum corneum barrier is commonly described according to the “brick and mortar” model constituted respectively by corneocytes and intercellular lipids; the former are composed mainly of insoluble bundled keratins surrounded by a cell envelope stabilized by cross-linked proteins and covalently bound lipids. Polar structures, such as corneodesmosomes, interconnect corneocytes determining stratum corneum cohesion. Intercorneocytic lipids are primarily generated from exocytosis of lamellar bodies during the keratinocytes’ terminal differentiation and secondarily generated by sebaceous output. Lipids are required for a competent skin barrier and homeostatic control of transcutaneous penetration. 1