The primary visual system of adult lizards demonstrates that neurogenesis is not obligatorily linked to central nerve regeneration but may be a prerequisite for the restoration of maps in the brain.

Following optic nerve crush in the adult lizard Ctenophorus ornatus, most retinal ganglion cells regrow their axons into visual brain centres: however, the regenerated projections lack retinotopic order and the animals are blind via the experimental eye. Here we have used 3H-thymidine autoradiography to demonstrate that cell division is no longer taking place in the retina of normal adult lizards. We conclude that the optic nerve can regenerate in lizard even though cells are no longer being added to the retina. However, continued retinal neurogenesis may be linked to the ability to restore topographic maps.