At this stage the regenerating stump undergoes changes that will allow the regeneration process to proceed. Cells near the amputation plane begin to dedifferentiate. That is they lose characteristics of differentiated tissues (e.g. muscle, cartilage, and connective tissue) and apprear to be undifferentiated. At this point, they begin to proliferate as "blastema" cells that interact to stimulate outgrowth and repatterning of the regenerate. Cell contribution studies have demonstrated that the majority of the cells that contriubute to the blastema are derived from cells of the limb connective tissues (fibroblasts).