As these cells wear away, they're replaced from beneath. The innermost part of the epidermis consists of rapidly dividing cells, called keratinocytes, which produce keratin, a tough protein. Epidermis also contains a unique fatty substance that makes skin waterproof. Hair follicles, sweat glands, and oil glands also reside deep in this layer, which is mainly connective tissue. A network of collagen, the most common protein in the body, gives flexibility and structural support to the skin.
Fibroblasts are the dominant cell type.
Dermis plays a role in preventing wound contraction and scarring. Treatment of burns depends on how deep and extensive they are, and the overall health of the patient. Second-degree burns damage the skin more deeply, causing blisters but sparing some of the dermal layer. Unless they're extensive, these burns usually heal without serious scarring. Third-degree burns destroy the full skin thickness, sometimes exposing muscle or bone, and require specialized treatment and skin grafts to obtain complete wound healing and reduce scarring.