Skin Grafts

[Birchy]

Why are skin grafts seemingly so large compared to the surface area they are covering? And are they really necessary if ones skin just heals anyway?

[Toglet]

If you have a large area uncovered by skin, you can die from dehydration - you need your skin to keep fluid inside the body! Left to its own devices the surface of uncovered flesh is likely to become infected (death by blood-poisoning) before scar tissue forms. Scar tissue is very stiff in comparison with healthy skin, so the victim may not be mobile afterwards.

[craig_edward]

Split skin grafting (where you remove part of the very top layer of skin from a healthy part of the body and put it on the wounded area) is a good way of healing large skin wounds. The healing graft undergoes contraction (which probably explains why the graft is large compared to the wound). There is also no guarantees that the whole graft will 'take' - the epithelial layer that you have grafted on needs to develop a blood supply (small capillary loops) in order to survive. Wounds which go below the basement membrane of the skin and are relatively large heal by scar formation - fibroblasts migrate into the area and lay down fibrous tissue, the normal skin architecture is lost and the wound heals with a white, fibrous scar tissue. If the wound is sufficiently small, then epithelial tissue (normal skin tissue) may grow into the wound and normal skin architecture is preserved - i.e. there is no scar formation.