<unk> , or auditory<unk> , consists of either of the two sac-like invaginations formed and subsequently closed off during embryonic development. It is part of the neural ectoderm, which will develop into the membranous labyrinth of the inner ear. This labyrinth is a continuous epithelium, giving rise to the vestibular system and auditory components of the inner ear. During the earlier stages of embryogenesis, the<unk>  placode invaginates to produce the<unk>  cup. Thereafter, the<unk>  cup closes off, creating the<unk> . Once formed, the<unk>  will reside next to the neural tube medially, and on the lateral side will be paraxial mesoderm. Neural crest cells will migrate rostral and caudal to the placode. The general sequence in formation of the<unk>  is relatively conserved across vertebrates, although there is much variation in timing and stages. Patterning during morphogenesis into the distinctive inner ear structures is determined by homeobox transcription factors including PAX2, DLX5 and DLX6, with the former specifying for ventral<unk>  derived auditory structures and the latter two specifying for dorsal vestibular structures.
Otic vesicle
Syrinx 
Ranula
Hemotympanum
Ateronon
Orbital septum
Lacrimal groove
Optic recess