The dorsal portion of the embryonic first endodermal pharyngeal pouch; it develops into the middle ear cavity.
Comment:
[homology-note] "The tympanic cavity and auditory tube of an amniote develop from the first embryonic pharyngeal pouch, so they are homologous to the first gill pouch, or spiracle, of a fish. We are uncertain whether this homology strictly applies to the middle ear cavity and auditory tube of lissamphibians, which show certain peculiarities in their development.[well established][VHOG]" xsd:string {date_retrieved="2012-09-17", external_class="VHOG:0001297", ontology="VHOG", source="ISBN:978-0030223693 Liem KF, Bemis WE, Walker WF, Grande L, Functional Anatomy of the Vertebrates: An Evolutionary Perspective (2001) p.417", source="http://bgee.unil.ch/"}