[Effect of hair cells and nerve growth factor on the differentiation of neurons of the cochleovestibular ganglion].

This study address the effect of hair cells, as target tissues and the nerve growth factor (NGF) on the survival and differentiation of murine cochleovestibular ganglion neurons. Isolated ganglia, ganglia with otic sensory epithelium and ganglia plus NGF were explanted from 12 gestation day mouse embryo and cultured for 14 days, in M-199 plus 10% fetal calf serum, on collage gel substrata. Histological and immunocytochemical studies, searching for cell degeneration and neurofilament (160,000 daltons) expression, have shown that there were significantly less survival as well as fewer differentiated cochleovestibular ganglion neurons in isolated ganglion explants, than either in explants of ganglia with hair cells or in those contained NGF (50 ng/ml) as a trophic factor. Our results confirm that hair cells exert a trophic effect not only on neuronal survival but on neuronal cytodifferentiation, and that the influence of hair cells on cochleovestibular ganglion neurons is mediated by nerve growth factor. A role for NGF on regeneration in the auditory system is suggested.