Mitosis does occur in cells which are slightly behind the advancing edge and the epithelium makes its way across the wound. Migration also requires dissolution of the complex system that anchors the epithelial cells to the basement membrane. Epithelial cells secrete collagenases and probably additional enzymes that digest other extracellular matrix components. At advancing front is usually only one or two cells thick. When the wound is completely covered the cells recover their usual shape and attach themselves to the basement membrane.
Squamous differentiation continues and the normal thickness of the epithelium is restored.
Insulin, glucagon and the thyroid hormones and even the extracellular matrix components fibronectin and laminin also play a role. Small blunt wounds heal faster than larger ones. Wounds in more highly vascularised areas also heal more rapidly than those in poorly vascularised area's. Also, wounds of skin which overlies bony surfaces do not heal well as wound contraction and adequate apposition of the edges is difficult to achieve. Ischaemia due to pressure or vessel obstruction prevents their healing.