part of develops from ends during starts during eye optic nerve cranial nerve II XAO:0000188 ON Cranial nerve that is continuous with the layer of nerve cells on the inner surface of the eye. It exits the neurocranium via the large optic foramen and is covered by a fibrous connective tissue sheath. It transmits visual information from the retina to the brain. xenopus_anatomy UBERON:0000941 opticus cranial nerve death optic stalk NF stage 33 and 34