SUPPORTING CELLS IN AVIAN VESTIBULAR ORGANS PROLIFERATE IN SERUM-FREECULTURE

Explants of saccules and utricles taken from hatchling chicks were cul tured in medium that contained fetal bovine serum and in serum-free me dium. The mitotic tracers [H-3]thymidine and bromo-deoxyuridine were a dded to the media to label proliferating cells. High numbers of labele d supporting cells were found in cultures that were maintained in both serum-containing and serum-free media. After seven days in culture, s ome of the labeled cells had begun to differentiate as hair cells. The results suggest that any mitogenic factors necessary for supporting c ell proliferation and the factors required for the initial stages of h air cell differentiation are produced by cells contained within explan ts of the vestibular sensory epithelia.