Epithelialization is the natural act of healing dermal and epidermal tissue in which epithelium grows over a wound. Epithelium is a membranous tissue made up of one or more layers of cells that contains very little intercellular substance.
Epithelialization is a complex process of tissue repair consisting of three overlapping phases.
When the skin is wounded, blood comes into contact with collagen that triggers blood platelets to secrete inflammatory factors. Homeostasis (stopping blood loss) takes place through the clotting cascade. Plasma proteins are released to attract cells that phagocytise (ingest foreign particles). This cellular migration to the wound area is the first line of defense against debris, bacteria, and damaged tissue.
Two to five days after the onset of the wound, patent cells begin to sprout cells (angioblasts) into the wound, forming new capillary loops. Type III collagen is produced forming "granulation tissue."
Remodeling begins when special cells (myofibroblasts) appear. Their muscle-like contracting proteins act on the wound as a whole, shrinking the wound.
Wound-healing disorders interfere with natural epithelialization. Chronic wounds can be recognized by a loss of skin around the wound. Such wounds can result in serious medical complications and require immediate and intense medical intervention.