4. Experimental Methods II. The Defect Closure Rule

Anatomically well-defined wounds (termed defects) in organs are considered to close by just three modes: contraction, scar (or neuroma) formation, and regeneration. Methodology for quantitative determination of relative contribution for each mode to defect closure is described. The experimental evidence is concisely summarized by the defect closure rule, which states that the percentages of initial defect area closed by each of the three closure modes add up to 100, i.e., %Contraction + %Scar + %Regeneration = 100, or C + S + R = 100. The rule describes the configuration of the final state (outcome) of defect healing by three numbers only, each corresponding to the relative contribution of a closure mode. It is a convenient quantitative summary of the outcome of a healing process independently of anatomical site.