Anatomy, histology and immunohistochemistry of normal human skin.

The skin is the largest organ of the body, accounting for about 15% of the total body weight in adult humans. It exerts multiple vital protective functions against environmental aggressions, rendered possible thanks to an elaborate structure, associating various tissues of ectodermal and mesodermal origin, arranged in three layers, including (from top to bottom) the epidermis (and its appendages), the dermis and the hypodermis. This article reviews the main data concerning the anatomy, histology and immunohistochemistry of normal human skin.