Assessing the skin barrier via corneocyte morphometry

The skin barrier is an inevitable physiological function. Virtually all skin diseases exhibit an altered barrier. Because of its diversity, this vital function cannot be assessed adequately by a single method. Preference in both pharmaceutical and cosmetic testing is given to noninvasive assays, mostly macroscopic methods like optical or electrical or mechanical measurements. The present review focuses on advances in ultrastructural assays based on corneocytes obtained via tape stripping-highlighting candidates for automated processing. Among these are electron microscopic (EM) and atomic force microscopic (AFM) analyses, which are discussed with respect to clinical signs and skin hydration, as assessed by Raman spectroscopy or by concentration of natural moisturizing factor.