part of part of has developmental contribution from contributes to morphology of immediate transformation of brain midbrain AAO:0010149 BAMS:MES BM:MB BTO:0000138 CALOHA:TS-0630 DHBA:10648 DMBA:16649 EFO:0000919 EHDAA2:0001162 EHDAA:3694 EMAPA:16974 EV:0100242 FMA:61993 Fine structural, computerized three-dimensional (3D) mapping of cell connectivity in the amphioxus nervous system and comparative molecular genetic studies of amphioxus and tunicates have provided recent insights into the phylogenetic origin of the vertebrate nervous system. The results suggest that several of the genetic mechanisms for establishing and patterning the vertebrate nervous system already operated in the ancestral chordate and that the nerve cord of the proximate invertebrate ancestor of the vertebrates included a diencephalon, midbrain, hindbrain, and spinal cord.[well established][VHOG] HBA:9001 MA:0000207 MAT:0000106 MB MBA:313 MESH:D008636 MIAA:0000106 Middle part of the brain composed of the optic tectum and penducular region.[AAO] OpenCyc:Mx4rvsBUqpwpEbGdrcN5Y29ycA RETIRED_EHDAA2:0001104 TAO:0000128 The brain region between the forebrain anteriorly and the hindbrain posteriorly, including the tectum dorsally and the midbrain tegmentum ventrally. Kimmel et al, 1995.[TAO] The midbrain is the middle division of the three primary divisions of the developing chordate brain or the corresponding part of the adult brain (in vertebrates, includes a ventral part containing the cerebral peduncles and a dorsal tectum containing the corpora quadrigemina and that surrounds the aqueduct of Sylvius connecting the third and fourth ventricles)[GO]. UBERON:0001891 UMLS:C0025462 VHOG:0000069 XAO:0000014 ZFA:0000128 developmental relationships need revised http://braininfo.rprc.washington.edu/centraldirectory.aspx?ID=462 mesencephalic mesencephalon part of brainstem in ABA - we reject this in favor of ISBN10:0471888893 which has an implicit overlaps relationships uberon hindbrain regional part of brain mesencephalic neural crest presumptive midbrain structure with developmental contribution from neural crest