Anatomy of Epidermis

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The epidermis (also called the cuticle or epithelial layer) is the outermost or surface part, and protects the more delicate underlying parts from trauma, chemical irritation, bacterial invasion, and other external factors. It may be conveniently divided into five layers, beginning with the most exterior: the stratum corneum, the outermost layer; the stratum lucidum, an ill-defined shining layer; the stratum granulosum, a granular layer; the stratum malpighii or rete mucosum; and the stratum germinativum. It must be remembered that, although described in this order, the layers probably largely originate in the opposite sequence; i.e., the stratum germinativum or basal cell layer gives origin to all the others. It was formerly thought that by reproduction the cells of this layer were multiplied and, being forced outward, underwent various differentiations which constituted their life history and culminated in the desquamation of the stratum corneum. However, recent studies of the healing of surgical wounds and of mitoses in the skin of various animals have shown that mitoses occur throughout the prickle cell layer as well as in the basal cell layer, and that the majority of cells growing over a wound are derived from the prickle cell layer of the old epithelium; a basal cell layer is later formed by modification of these prickle cells. More: http://skindiseasencare.com/epidermis/