Zebrafish parapineal development

During zebrafish brain development, a small group of cells delaminates from the pineal organ and migrates to the left as a rosette to form a parapineal, which sends out unilateral axon projections to habenular nuclei. The parapineal conveys photoreceptive information to the pineal gland, which secretes melatonin to regulate sleeping patterns. Formation and migration of the parapineal underlies the development of left-right asymmetries in the dorsal diencephalon. The width of the parapineal is approximately 100 micrometres.