 In one case, however, a particular type of collagen graft led to significant delay of wound closure.Careful study of histology samples revealed that grafts that delayed wound closure induced the synthesis of new dermis de novo at the injury site, instead of forming scar, which is the normal outcome of the spontaneous wound healing response.This was the first demonstration of regeneration of a tissue (dermis) that does not regenerate by itself in the adult mammal.