[The existence of vasomotor nerve in the retina of the rabbit and monkey]

In the first stage of this study, peri- or intravascular unmyelinated nerve axon which was clearly different from that of the optic nerve was confirmed in the rabbit retina transmission electron microscopically. In the second stage, the correlation of these unmyelinated nerves and autonomic nerve was studied in rabbits and monkeys. For the purpose, wheat germ agglutinin horseradish peroxidase (WGA-HRP) was injected into the superior cervical ganglion. Electron microscopic observation of the retina 48 hrs after the injection of WGA-HRP showed deposit of its reaction product in the axon of the unmyelinated nerve located around the vascular wall and in the adventitia and smooth muscle cell in both rabbits and monkeys. This result clearly reveals the existence of an autonomic vasomotor in the retinal vessels at least in rabbits and monkeys.