Wound Healing Stages

A deep cut sets off the same repair sequence every time, in four overlapping phases:

• Clotting: within seconds, blood seals the breach.
• Inflammation: within hours, immune cells arrive to clean the wound.
• Rebuilding: over days, new tissue fills the gap.
• Remodeling: over months, the patch is reorganized and strengthened.

The phases blend into each other rather than waiting in a tidy line.

There is one striking exception to scarring. Early in development, a fetus heals wounds without any scar at all — the skin knits back as if nothing happened.

Somewhere before birth, skin loses that ability and switches to the fast, scar-forming repair adults use. Researchers are studying what changes in that switch, because copying the fetal version could one day mean healing without scars. For now, it remains one of the body's most tempting unsolved problems.