A lineage specific enhancer drives Otx2 expression in teleost organizer tissues

► Otx2 is essential to head development in visceral endoderm, mouse organizer. ► Enhancer for this Otx2 expression is conserved in tetrapod but not teleost. ► In teleost, Otx2b, but not Otx2a, remains active in organizer tissues. ► The enhancer for this Otx2b expression is not homologous to tetrapod Otx2 enhancer.