Fig. 5.
Brain regeneration in salamanders. (Top) Brain regeneration following injury (e.g. unilateral forebrain extirpation) presumably occurs by activation of ependymoglial cells. Neuronal diversity is restored but projections are not a faithful replication of the original. The time frame shown here is based on studies in the axolotl. (Bottom) Studies on red-spotted newts have showed that dopaminergic and cholinergic (not shown) neurons regenerate in several brain regions after the selective ablation of individual neuronal subtypes. Injury-responsive neurogenesis is fuelled by reactivation of quiescent resident neuronal progenitor cells, the ependymoglial cells, which are the equivalent of glial cells in mammals.