We have shown previously that intravitreous transplantation of a peripheral nerve (PN) graft stimulates a subpopulation of retinal ganglion cells (RGCs) to sprout axon-like processes. The present study examined whether the effect of PN graft was due to diffusible factors released from the graft. Injection of sciatic nerve exudate into vitreous of the eye induced the formation of axon-like processes. Significantly more RGCs with axon-like processes were stained after injection of exudate from the distal stump than the proximal stump of the transected sciatic nerve. Thus, our results showed that trophic factors released from the intravitreous PN can induce the formation of axon-like processes and that more trophic factors are secreted from the distal than the proximal stump of the transected sciatic nerve.