A scar is formed as a result of the wound healing process. Wound healing can be divided into three main stages: inflammation, proliferation and remodeling. The first stage is inflammation, which begins when there is damage to the skin and the capillary blood vessels within it, triggering the clotting cascade. A matrix composed of fibrin clots and platelets is deposited in the wound and signals the migration of various cells that take part in the wound healing process.
The second stage of wound healing is proliferation, which begins around day 4 or 5 with the migration of cells called fibroblasts into the wound matrix. Fibroblasts are responsible depositing collagen, which is the main component of scars. By 2 to 4 weeks, the wound matrix has been replaced with collagen fibers. Another important part of the proliferation stage is wound contraction, which begins around day 10 to 12, but timing can vary depending on wound severity and other factors.
The third and final stage of wound healing is remodeling, which usually begins 3 weeks after tissue injury. During this stage, a hardening of the collagen fibers occurs. Continuous collagen production and degradation occurs for about 6 months after the initial injury, after which a balance is achieved, and there is no significant change in the amount of collagen in the wound. The remodeling stage is the most responsible the variations seen in scars. A healing wound can become an unsightly scar during this stage.