High‐resolution X‐ray tomography of the human inner ear: synchrotron radiation‐based study of nerve fibre bundles, membranes and ganglion cells

Summary The combination of osmium tetroxide staining and high‐resolution tomographic imaging using monochromatic X rays allows visualizing cellular structures of the human inner ear, that is, the organ of Corti, the stria vascularis and further soft tissues of the membranous labyrinth, in three‐dimensional space with isotropic micrometre resolution. This approach permits to follow the course of nerve fibre bundles in a major part of the specimen and reveals the detailed three‐dimensional arrangement of individual ganglion cells with distinct nuclei by means of X‐ray tomography for the first time. The non‐destructive neuron cell counting in a selected volume of 125 μm × 800 μm × 600 μm = 0.06 mm 3 gives rise to the estimate that 2000 ganglion cells are present along 1 mm organ of Corti.