SENSORY CELLS OF THE CHICK COCHLEA EXPRESS SYNAPTOPHYSIN

Previous evidence has shown expression of synaptophysin by sensory cel ls of the auditory and vestibular systems in the human, brit not in ot her mammalian species. Using a monoclonal antibody, SBI 20.10, we inve stigated the expression of synaptophysin in the sensory cells of the a vian cochlea. We present immunohistochemical data showing synaptophysi n expression by cochlear hair cells in both late stage embryos and adu lt chickens. Immunoblotting of cochleae confirmed an antigen with an a pparent molecular weight appropriate for synaptophysin that increases with development. Immunoreactivity in the apex of the cochlea occurred in hair cells on both neural and abneural sides, whereas immunoreacti vity in the base of the cochlea was relegated to hair cells on the neu ral side. These observations indicate that, in the avian auditory syst em, like the human, synaptophysin is expressed in the sensory cells of both the embryo and adult.