Synopsis

A comparative analysis of surface and ultrastructural changes in stratum corneum (SC) with transepidermal water loss (TEWL) was conducted to develop a better understanding of the surfactant-induced damage to human skin. Treatments comprised a synthetic hnionic surfactant (A), a composition of soap, glycerin, and petrolaturn (B), a pure soap (C), and water (control). An increase in water loss is shown to correlate with increased perturbation of lipid barrier and damage to multiple layers of corneocytes. Transmission electron microscopy (TEM) revealed that, in general, one to two layers of lipid lamellae enveloped the outer layers of SC throughout he tissue. A significantly larger number of lamellae (approximately six to eight) appeared only in the lower layers. Surface topology, obtained using environmental scanning electron microscopy (ESEM), displayed a normal unperturbed structure. Treatment with A did not result in significant changes in SC. B caused regional variations in corneocytes and an increase in TEWL. Treatment with C exhibited significant variation in TEWL numbers: lipid lamellae were disordered and corneocytes appeared damaged and swollen. Intercorneocyte damage ranged from one to two (for TEWL- 11 g/m 2 hr) to up to six cell layers (for TEWL- 34 g/m 2 hr) of the SC. The presence orabsence ofthe outermost layers of disjunctum did not appear to be critical for water loss, presumably due to a decrease in lipid lamellae