Permalink : http://hdl.handle.net/2115/38490

KEYWORDS : Phylogeny;Ontogeny;Amphibians;Xenopus laevis;Metamorphosis

This brief paper lays a conceptual link between ontogeny and phylogeny in vertebrate regeneration, inspired by the investigation in an anuran amphibian. Regenerative ability in Xenopus declines most rapidly after the climax of metamorphosis. In order to analyze the cause of this decrease during metamorphosis, we have made comparative experiments in larvae and adults after removing the anterior half of telencephalon. As a result, it was found that brain cells actively proliferated even in non-regenerating adults, just as in regenerating larvae, after partial removal of the telencephalon. Moreover, it was found that even adult-brain-derived dispersed cells reconstituted a subnormal structure of the lost part when transplanted to the partially truncated telencephalon. We consider that it is critical for the ependymal cells to cover the cerebral ventricle at an initial stage of wound healing, for massive organ regeneration, as is the case in larvae. On the other hand, in adults, these cells are strongly stuck in position and unable to move to seal off the exposed ventricle, which probably make the adult brain non-regenerative.