ABSTRACT
INTRODUCTION The skin plays a vital role in enabling our terrestrial existence by protecting our bodies from various influences of the environment. Unlike those epithelia of mucous membranes covering the digestive tract, respiratory tract, and genitourinary tract, which are not provided with effective physicochemical barrier function, epidermis, the epithelial tissue of the skin, produces an extremely thin but highly efficient barrier membrane, stratum corneum (SC) (1). The SC is less than 20 mm thick, yet it can protect the underlying hydrated living tissues from desiccation by preventing water loss even in a dry environment as well as prevent the invasion of various external injurious agents. In fact, those substances larger than 500 Da in molecular size can hardly permeate through the SC.
