Morphometric and ultrastructural findings on human vestibular ganglion cells

Eight human temporal bones (4 patients) were fixed within 2 h after death by perilymphatic perfusion through the oval and round windows. After preparation, 30-micron-thick sections were cut for light microscopy and ultrathin sections for ultrastructural evaluation. Under the light microscope, the diameter, the circumference and the area of the vestibular ganglion cells were measured. The data were statistically analyzed. The histograms of cell measurements showed two maxima. When observing the diameter of cells, one was at 40 microns and the other at 28 microns. Under the light microscope, we could distinguish two cell types, which mainly differed in size and content of granules in the cytoplasm. Ultrastructurally we identified also two cell types: larger cells with many mitochondria, dark clusters of endoplasmic reticulum and a varying amount of dark-stained lysosomes in the cytoplasm and smaller cells with only few mitochondria, no lysosomes and an extended rough endoplasmic reticulum. None of the ultrastructurally analyzed ganglion cells were myelinated.