ASPARTATE IS ENRICHED IN SENSORY CELLS AND SUBPOPULATIONS OF NONNEURONAL CELLS IN THE GUINEA-PIG INNER-EAR - A QUANTITATIVE IMMUNOELECTRON MICROSCOPIC ANALYSIS

The cellular and subcellular localization of aspartate in the guinea p ig inner ear was studied by means of quantitative postembedding cytoch emistry. High levels of aspartate immunoreactivity were found in neuro nal compartments, including all types of hair cells, and afferent and efferent nerve fibers. In addition, sub-basilar tympanic cells, interd ental cells, and the mesothelial cells in the Reissner's membrane were strongly immunoreactive. The present immunocytochemical results are c onsistent with the idea that aspartate is involved in neurotransmissio n in the inner ear, but also point to possible metabolic roles of aspa rtate.