Course of the accessory optic fascicular fibers in the rat

The courses of fibers in the dorsal and lateral fasciculi of the accessory optic tract were studied in the rat by means of a selective silver impregnation method for degenerating nerve fibers and Mesulam's HRP method. The results indicate that except for a moderate number of fibers entering the dorsal terminal nucleus and the lateral terminal nucleus respectively, all optic fibers constituting the dorsal and lateral fasciculi descend the lateral surface of the brain to terminate in the medial terminal nucleus. No ascending optic nerve fiber to the dorsal or lateral terminal nucleus is included in these fasciculi.