The evolutionary origin and mechanism of chordate tail regeneration. An ancient tale?

Chordate tail regeneration represents the remarkable ability of some chordates to partially or completely regenerate a significant portion of their primary body axis. In this review we will discuss the chordate regenerative ability, what is known about the cellular sources which contribute to the regenerating tail, how various structures such as the spinal cord and vertebral column are re-established, and how scaling of the regenerating tail is regulated. Finally, we propose that tail regeneration is evolutionarily conserved and is fundamentally different from tail development however the origin and mechanism of this process remain elusive.