 Salamanders ' limb regeneration has long been the focus of interest among scientists . Researchers have been trying to find out the conditions required for the growth of new limbs and hope that such regeneration could be replicated in humans using stem cells . <unk> have been used in research and have been genetically engineered so that a fluorescent protein is present in cells in the leg , enabling the cell division process to be tracked under the microscope . It seems that after the loss of a limb , cells draw together to form a clump known as a <unk> . This superficially appears undifferentiated , but cells that originated in the skin later develop into new skin , muscle cells into new muscle and cartilage cells into new cartilage . It is only the cells from just beneath the surface of the skin that are pluripotent and able to develop into any type of cell . Researchers from the Australian Regenerative Medicine Institute have found that when macrophages were removed , salamanders lost their ability to regenerate and instead formed scar tissue . If the processes involved in forming new tissue can be reverse engineered into humans , it may be possible to heal injuries of the spinal cord or brain , repair damaged organs and reduce scarring and fibrosis after surgery . 
