ABSTRACT
Barrier . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 2.6 The Ceramides of the Human Skin Barrier . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 2.7 Free Fatty Acids and Cholesterol . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 2.8 Lipid Gradients within Stratum Corneum . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 2.9 Structure of Stratum Corneum — Barrier Models. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
2.9.1 The Brick and Mortar Model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 2.9.2 The Domain Mosaic Model. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 2.9.3 The Single Gel Model and the Sandwich Model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
2.10 Properties of the Lamellar Barrier — Effects of Penetration Enhancers . . . . . . . . . . . . . . . . . 17 2.11 Conclusions — Barrier Penetration in a Functional Perspective. . . . . . . . . . . . . . . . . . . . . . . . . . 17 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
This chapter will deal with the stratum corneum barrier with a special focus on structure-function relationships. For this reason our approach has been to describe some details of the epidermal physiology that have a bearing on upholding the barrier function. We see it as important that skin barrier function is regarded as part of the dynamic processes of cellular transformation during the differentiation of epidermal keratinocytes, hence dependent on the status of the skin.
