Internal ear

At S10, an ectodermal thickening arises in the surface ectoderm at the level of the rhombencephalon, called the otic placode or otic disc. At S11, it invaginates to form the otic pit (fovea otica). At S13, this gives rise to the otic vesicle (vesicula otica) which separates out from the surface ectoderm and forms the epithelial lining of the membranous labyrinth . A vertical folding of its anterior wall causes a tube-like diverticulum to appear on the medial aspect. At S14, this diverticulum differentiates into the ductus and saccus endolymphaticus. Neural crest cells originating from the otic placode, the rhombomere 4 and the internal ear vesicle give rise to cells of the vestibulocochlear ganglion.