Restoration of vision in genetically eyeless axolotls (Ambystoma mexicanum).

Eyes grafted into genetically eyeless axolotls at embryonic stages 26 or 27 (early tailbud stage) are capable of establishing retinotectal connections and restoring near normal vision. Normal vestibulo-ocular reflexes are also present in most of the eyeless mutants having grafted eyes. The animals are capable of accurately localizing objects in visual space and demonstrate following movements in an optokinetic drum. Evoked potentials can be recorded from the surfaces of the tectal lobes of eyeless mutants having a right eye graft which do not differ significantly from those recorded from a normal animal, except that recordings can still be obtained from the ipsilateral tectal lobe in the former following section of the intertectal fibers. This indication of direct retinotectal connections to the ipsilateral tectum was confirmed by histological examination which also showed that the optic fibers entering the diencephalon high on the lateral wall are initially directed toward the normal optic tract position before proceeding to be tectum.