title: Induction of the chick columella and its integration with the inner ear.
abstract: BACKGROUND
  The auditory complex of the chick, like that of humans, is made of intimate and highly ordered connections between the inner ear, the middle ear, and the outer ear. Unlike mammals, the middle ear of chick has only one ossicle, known as the columella. The independent lineages of the two suggest that some mechanism must exist that ensures the connectivity between the inner ear and the columella; however, the basis of integration is not known.
  
  
  RESULTS
  Using quail-chick chimeras, we demonstrate that columella development depends on signaling interactions. Specifically, both pharyngeal endoderm and cranial paraxial mesoderm can alter the morphology of the columella. Only a discrete region of pharyngeal endoderm exerts this patterning activity, and this region is specified by the overlying paraxial mesoderm.
  
  
  CONCLUSIONS
  Paraxial mesoderm is also used in the induction of the inner ear, thus we propose that this overlapping source of signalling cues in both middle and inner ear development may underlie the integration of these structures.
authors.affiliation: RIKEN Center for Developmental Biology, Kobe, Japan.
authors.forename: Yihui
authors.initials: Y
authors.lastname: Zou
authors.forename: Siu-Shan
authors.initials: SS
authors.lastname: Mak
authors.forename: Hui Zhan
authors.initials: HZ
authors.lastname: Liu
authors.forename: Dong Yi
authors.initials: DY
authors.lastname: Han
authors.forename: Hong Xing
authors.initials: HX
authors.lastname: Zhuang
authors.forename: Shi Ming
authors.initials: SM
authors.lastname: Yang
authors.forename: Raj K
authors.initials: RK
authors.lastname: Ladher
mesh_terms: D000423:Alcian Blue; D000818:Animals; D002642:Chick Embryo; D002678:Chimera / Q000196:embryology; D004429:Ear Ossicles / Q000196:embryology*; D007758:Ear, Inner / Q000196:embryology*; D004627:Embryonic Induction / Q000502:physiology*; D004707:Endoderm / Q000502:physiology*; D007150:Immunohistochemistry; D008648:Mesoderm / Q000502:physiology*; D009024:Morphogenesis / Q000502:physiology*; D011784:Quail; D015398:Signal Transduction / Q000502:physiology*
chemical_list: D000423:Alcian Blue