Epidermis

The outermost layer of the skin, 0.1 to 1.5 mm thick depending on body area. The epidermis is mainly composed of keratinocytes that migrate from the basal layer to the surface while progressively differentiating, forming the stratum corneum that constitutes the main physical barrier. It also contains melanocytes (melanin producers), Langerhans cells (immunity) and Merkel cells (tactile sensitivity). It renews completely every 28 to 30 days.