Auditory canal embryology

The medial-developing external auditory canal becomes filled with the meatal plug, consisting of proliferating ectodermal cells that subsequently recanalize. The tubotympanic recess has deepened to form the tympanic cavity. The otic vesicle forms the endolymphatic duct and sac, early semicircular canals, and cochlear diverticulum. The membranous labyrinth induces surrounding mesenchyme to condense and ultimately form the stapes, incus, and malleus.