Retinal transplants can drive a pupillary reflex in host rat brains.

Retinae taken from embryonic rats were transplanted over the midbrain of neonatal rats, from whom one eye had been removed. After 5 months, the optic nerve of the remaining eye was cut, and the transplant was exposed. Illumination of the transplant caused pupilloconstriction of the host eye, a response abolished by damaging the transplant. Thus neural transplants are capable of driving specific reflexes in response to natural stimuli.