Recently, cultured skin equivalents of human origin have become available. These materials, also known as living skin equivalents (LSEs), are made up of human cells and matrix equivalents normally present in skin. LSEs closely resemble human skin, consisting of a dermis and a stratified epidermis with a well-differentiated stratum corneum (Ponec et al., Toxicity screening of N-alkylazaicycloheptan-2-one derivatives in cultured human skin cells: structure-toxicity relationships, J. Pharm. Sci., 78 (1989) 738-741; Ponec et al., Nitroglycerin and sucrose permeability as quality markers for reconstructed human epidermis, Skin Pharmarcol., 3 (1990) 126-135) but lack the structural appendages found in human skin (e.g., hair follicles, sweat glands)