develops from contributes to morphology of immediate transformation of Eumetazoa brain nervous system central nervous system metencephalon the terms metencephalon and myelencephalon are only meaningful in mammals and birds[Neuroanatomy of the Zebrafish Brain]. In zebrafish, with the exception of the cerebellum, the ventral remainder of the metencephalon can be separated only arbitrarily from the more caudal myelencephalic portion of the medulla oblongata and thus these are not distinguished in ZFA[ZFA]. hindbrain ectoderm-derived structure segmental subdivision of hindbrain future metencephalon