Segregation of optic fibre projections into eye-specific bands in dually innervated tecta in Xenopus.

The restoration of the retinotectal projections following metamorphic bilateral optic nerve sections was studied in Xenopus 20 weeks after operation, using [3H]proline autoradiography and electrophysiological mapping. Optic fibre projections from each eye to both tecta segregated into eye-specific termination bands with some overlap at the borders. The bands were arranged rostrocaudally in the tecta such that each eye had an alternating representation. Despite the segregation of the optic fibres, each eye had a complete visual (retinal) projection with the normal nasotemporal and dorsoventral polarities of the visual field maintained. The results suggest competition for preferred terminal sites between the two sets of optic fibres in dually innervated tecta.