HAIR-CELL REGENERATION IN ORGAN-CULTURES OF THE POSTNATAL CHICKEN INNER-EAR

The sensory epithelium of the avian inner ear retains into adulthood p rogenitor cells for inner-ear hair cells and other cell types in the e pithelium. Hair cells are produced normally on an ongoing basis in the vestibular sensory epithelium, and hair-cell production is increased after insult in both auditory and vestibular sensory epithelia. The de tails of postnatal hair-cell production are not understood. In particu lar, molecular factors involved in the initiation and regulation of ha ir-cell genesis and differentiation are not known. Studies of this phe nomena have been hampered by the lack of cell culture models. An organ culture system was developed which encourages generation and differen tiation of hair cells in mature inner-ear sensory epithelia. Continuou s labeling with tritiated thymidine showed genesis of both supporting cells and hair cells in normal vestibular epithelia grown in culture, and an increase in hair-cell and supporting-cell proliferation in dama ged sensory epithelia grown in culture as compared to undamaged contro ls. This demonstrates, in vitro, both the division and differentiation of hair-cell progenitor cells in normal vestibular epithelia, and the maintenance of the hair-cell regeneration process in damaged inner-ea r epithelia. This culture system should be useful for studies of hair- cell genesis and differentiation as well as studies of hair-cell and s upporting-cell functioning in general.