Retinofugal sprouting of ipsilateral projections in rat

Expansion of ipsilateral retinal inputs into terminal regions of the primary was assessed in rats enucleated at birth or as adults. In addition, one animal with a congenital absence of one eye received an injection of the label into the remaining eye and was similarly processed. Analysis of the sections revealed an increase in retinal inputs, relative to control injections, in the lateral geniculate nucleus and the superior colliculus. The increase observed in the brains of animals receiving enucleation at birth was greater than the increase observed after eye removal in the adult, although the greatest increase was observed in the animal with the congenital loss of one eye. Differences in the sprouting response within the various terminal areas as well as the age related decrease in the ability of retinofugal axons to sprout into denervated visual areas in the brain are discussed.