Regeneration of retinal axons in grafts of peripheral and central nervous tissue in the adult rat

Peripheral nerves were autologously grafted to the retinae of adult rats. The distal end of the nerves was inserted into fetal tectal tissue placed within cortical lesion cavities. Two to 8 months later, anterograde pathway tracing using horseradish peroxidase demonstrated retinal axons regenerating along the length of the PNS nerve graft in 87% of animals with viable PNS and fetal tectal grafts. Of these animals, retinal axons grew into the tectal neuropil in 23% of cases but specific innervation of appropriate target regions was not detected.