According to other authors, basal epithelial layers of the graft remain intact and represent the focus of reepithelialization. new epithelial cell migrate over the basal membrane and appear to guide it and by proliferation ,will generate new epithelium. so the wound is re-epithelialized by proliferation of surrounding healthy epithelial cell, therefore, not contaminated by modified antigens of the cell membrane that are theoretically responsible for lymphocyte aggression so the healthy graft remains free of lesions and appears clinically healthy.