ABSTRACT
Introduction 199 The Influence of Changes in Overall Skin Hydration
on the Mechanical Properties of Skin 201 Moisturizers and Skin Plasticity 202 Comments 204 References 204
INTRODUCTION The physical properties of the skin vary with location, age, and sex; but in addition to these endogenous factors, skin hydration is also thought to play a role. Skin consists of two main layers: epidermis (thickness 0.07 to 0.012 mm) and dermis (thickness 1 to 4 mm). Data suggest that both contribute to the overall mechanical properties of the skin, but only the epidermis is available for rapid modification by topical agents either directly or indirectly by, for example, reducing water loss. Topical treatment may also affect the dermis secondarily (e.g., by retinoids), although the timeframe is often much longer for this to occur. Finally, the dermis may be affected by generalized changes in the body. The mechanical effects of skin hydration can therefore involve several different structures.
