Retinal axons to the medial terminal nucleus of the accessory optic system in old world monkeys

Horseradish peroxidase (HRP) and HRP conjugated to wheat germ agglutinin (WGA-HRP) were used as anterograde tracers in the monkey visual pathways. In addition to known optic pathways, we observed labeled fibers which left the lateral terminal nucleus of the accessory optic system, traveled around the cerebral peduncle, and could be followed as far as the medial terminal nucleus.