part of part_of develops from embryo ectoderm ear vesicle OV The saccular invagination of ectoderm from which the vertebrate inner ear develops[BTO]. Epithelial sac present beside the fifth rhombomere; forms the semicircular canals dorsally and the otolith organs ventrally, and houses the acoustico-vestibular sensory epithelia (maculae) of hair cells[ZFA]. epithelial sac of invaginated ectoderm formed from the otic placode that gives rise to the structures of the inner ear[MP] acoustic vesicle auditory vesicle otic vesicle otocyst ectodermal placode embryonic tissue developing epithelial placode otic cup structure with developmental contribution from neural crest ecto-epithelium