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“How is regeneration of the spinal cord in the salamander related to its initial development ? There is now evidence that in the salamander, the steps of progenitor cell-patterning and controlled neurogenesis that naturally regenerate a severed tail largely recapitulate the steps followed during early embryonic development to initially build the central nervous system. For example, ependymal cells are descendants of radial glial cells retained from the earliest developmental stages in regenerating vertebrates. The ependymal tube that gives rise to regenerated spinal cord following salamander tail amputation is very similar in appearance to the early structure of the neural tube of developing amniotes. But how does that recapitulation occur ? By using a transgenic axolotl that expresses green fluorescent proteins (GFPs), they further examined the regenerated spinal cord by replacing a segment of the spinal cord from a typical animal with a piece of the spinal cord from a GFP-expressing animal - that is, one with green fluorescent cells. They found that the implanted cells in the experimental animals regenerated a green spinal cord ! Thus, regeneration may be a more neural stem-cell like, or pluripotent, state as a response to injury.”
― Eugene C. Goldfield, Bioinspired Devices: Emulating Nature’s Assembly and Repair Process