Regeneration - occurs when the new cells are of the same type and can perform the same function as the original structure. E.g., dermal tissues. Replacement - results when a different type of cell replaces the damaged cells. Excessive amount leads to scar tissue development. Macrophages and polymorphs, which can withstand low-oxygen environments, begin to laydown capillary beds.
Fibroblasts begin laying down collagen to form a seal over the injured structure.
Wound Contraction - occurs following the revascularization of the injured area. Also begins at the periphery and moves to the center of the injured area. Fibroblasts produce weak type III collagen. Water is drawn to the area of repair, and blood vessels, proprioceptive nerves, and sensory nerves begin to develop. With time, the strength of the scar is increased by the replacement of the old colagen with a newer, stronger type.