ABSTRACT
INTRODUCTION Dehydration of the stratum corneum is a typical feature of skin ageing, especially in photoaged skin, and of several diseases, for example, eczema, atopic dermatitis, psoriasis, and hereditary ichthyosis [e. g., (1-3)]. Water homeostasis of the epidermis is essential for the normal function of the skin and for normal SC hydration. It is a determinant of skin appearance, mechanical properties, barrier function, and metabolism. In addition, it is indispensable for water balance of the body (4-6). Furthermore, SC hydration appears to be directly linked to epidermal hyperplasia and inflammation which argues for a biosensor function of water content (7,8).
