CHARACTERIZATION OF DIFFERENT NEURON POPULATIONS IN MOUSE STATOACOUSTIC GANGLION CULTURES

Statoacoustic ganglion (SAG) cells were grown in primary culture and t he appearance of different neuronal phenotypes was investigated. Analy sis criteria were shape, size and staining for the immunocytochemical markers: neurofilament proteins (NF-200 kDa), neuron-specific enolase (NSE), calretinin, a calcium-binding protein and substance P, a neurot ransmitter. Cultures were prepared from dissociated SAG cells of 13 ge station-day-old mouse embryos. Neurons were identified and counted aft er 7 days in vitro. At this stage, neurons were organized in small clu sters forming an extensive network of neurites grown on a layer of fib roblasts and glia. Most neurons identified by NF or NSE immunoreactivi ty showed a typical adult-like bipolar profile. The diameters of the n eurons were between 5.62 and 17.00 mu m and displayed a normal distrib ution (mean: 10.6 mu m). Two distinct subpopulations were identified b y the expression of calretinin and substance P. Calretinin-immunoreact ive neurons were large and very rare and had a mean diameter of 11.3 m u m; the distribution of substance P was more extensive than that of c alretinin and identified a population of small neurons with a mean dia meter of 8.9 mu m. The distributions of these two markers in SAG cultu res were consistent with in vivo results. In conclusion, dissociated S AG cell cultures appear to be a suitable model for analyzing the devel opment of the immunocytochemical and functional characteristics of the neurons of this inner ear ganglion.