Ventral part of the midbrain, separated from the hindbrain by the isthmus[ISBN:0471888893]. Subdivision of the midbrain lying anterior to the tectum and posterior to the substantia nigra and cerebral peduncle[FMA] The part of the midbrain extending from the substantia nigra to the cerebral aqueduct in a horizontal section of the midbrain. It forms the floor of the midbrain that surrounds the cerebral aqueduct[WP].
Comment:
'tegmentum' is used generically for the ventral part of the brainstem (ISBN:0471888893). We use the label 'midbrain tegmentum' to denote the midbrain structure. In NIFSTD tegmentum is a composite structure and there is a separate class for midbrain tegmentum and pontine tegmentum; [homology-note] "Together, our results reveal a shared basic organization in the tegmental domains of the diencephalon and midbrain of developing lamprey, indicating early appearance of the domain in vertebrate phylogeny.[well established][VHOG]" xsd:string {date_retrieved="2012-09-17", external_class="VHOG:0001367", ontology="VHOG", source="DOI:10.1016/j.brainresbull.2005.05.001 Villar-Cheda B, Abalo XM, Anadon R, Rodicio MC, The tegmental proliferation region in the sea lamprey. Brain Research Bulletin (2005)", source="http://bgee.unil.ch/"}