Regeneration of the Vertebrate Tail

Abstract

Some vertebrates can regenerate their tail, a complex process which involves recruitment and proliferation of progenitor cells from the stump and their subsequent differentiation into the various tissues of the tail. Regeneration is observed only in tails that contain the spinal cord and their ability to regenerate varies among species and with age. Adult tailed amphibians (urodeles) have the most striking regenerative capability and frogs (anurans) can regenerate at larval stages. The spinal cord provides neural progenitor cells from which a new spinal cord will form and in urodeles has a key role in differentiation and morphogenesis of other tail tissues. In anuran tadpoles tail regeneration requires also the presence of the notochord to proceed. Tail regeneration occurs also in lizards, though less faithfully than in urodeles. Recent establishment of effective tracking techniques in amphibians and cloning of their genome is starting to fill the gap in our knowledge of the mechanistic control of tail regeneration. Key Concepts: The presence of the nervous system is crucial to tail regeneration. Caudal autotomy is associated with regenerative ability in lizards but not in urodeles. Paedomorphosis does not appear to be causally associated with regenerative ability, but continuous growth throughout adulthood correlates with high regenerative capability of all tissue tails including the spinal cord. Neural progenitor cells for regeneration in amphibians maintain an intermediate phenotype between radial glia and ependyma and are likely to be multipotent. Cells in regenerating tails largely maintain their identity and position of origin. Redeployment of certain developmental mechanisms underlies patterning in the regenerating tail.