The skin is a complex organ covering the whole surface of the body, and is continuous with the mucous membranes lining the body's orifices. It accounts for about 15% of the total adult body weight, and is therefore the largest organ of the body. It exerts multiple vital functions (namely of protection against external physical, chemical and biological aggressions), rendered possible thanks to an elaborate structure, associating tissues of various origins (epithelial, connective, vascular, muscular and nervous). These are organised in three layers, including from top to bottom: a) the epidermis (and its associated appendages, pilosebaceous follicles and sweat glands); b) the dermis, separated from the epidermis by the dermal-epidermal junction, and c) the hypodermis. The fine structure of the skin shows considerable regional variations, concerning its thickness (varying from 1 to 4 mm), distribution of epidermal appendages, density of melanocytes, to name but a few. Glabrous (hairless) skin is found on the palms and soles, whereas hair-bearing skin covers the rest of the body. Embryologically, the epidermis and its appendages are of ectodermal origin whereas the dermis and hypodermis are of mesodermal origin [1-3].