The Human Spiral Ganglion

Abstract

The adult normal human spiral ganglion (SG) was analyzed with regard to ultrastructure and immunohistochemistry. The cytoskeleton of the SG cells was found to comprise F-actin, intermediate filaments (IFs) and microtubules (MTs). The IF subgroups (cytokeratins, Cks; neurofilaments, NFs, vimentin, glial fibrillary acidic proteins, GFAP; desmin) displayed characteristic staining patterns. Ck No. 8 was found in all SG cells, whereas vimentin was lacking. GFAP stained only a small subpopulation of SG cells (type 2?). The light (68 kD) and medium-sized chains of NFs occurred in all SG cells and axons, whereas the 200-kD NF subunit was only found in the axonal hillock of (type 2?) SG cells, but in no other part of the cytoplasm, and regionally in nerve fibres. MAP-1 and MAP-2 occurred in all SG cells but only MAP-1 was found in the nerve fibres. The calcium-binding protein synaptophysin (SY) was expressed only in SG cells, in contrast to the S-100 which occurred more generally in the labyrinth. The neuropeptides VIP and substance P were identified in all SG cells, in contrast to NPY which was expressed in a small sub-population of SG cell (type 2?). Staining for neuron-specific enolase (NSE) identified most (type 1?) but not all SG cells. The cell surface glycoprotein Thy-1 was expressed in SG cells in a way similar to that described for neurons in the CNS. The SG cells express a high degree of cytoskeletal complexity, allowing one to distinguish between type 1 and type 2 cells. The cell bodies and their adjacent nerve fibres show characteristic features of calcium-binding proteins, surface membrane glycoproteins, NSE and neuropeptides but the basic pattern is still similar to neurons in the CNS.

Image Analysis of Neurofilament Immunoreactivity in Human Spiral Ganglion

“…The specific staining of type-2 cells for mAb NF-H is attributable to the abundant, highly phosphorylated NF-H, which seems to be necessary for the imme diate assembly of NFs in order to stabilize the cytoskeleton [10], The specificity of mAb NF-M for type-1 cells can ORL 1997;59:258-262be explained by its larger axon diameter with more NFs as observed in the dorsal root ganglion [21,22] and vestibu lar ganglion [9], though its functional implication needs to be clarified. mAb NF-H has been noted to stain type-2 spiral gan glion cells specifically [2, 6-8, 10, 12-15], which can pos sibly be attributed to the more abundant NFs in type-2 cells than in type-1 cells as identified ultrastructurally [23,24], Our findings on the distribution of NF-M are consis tent with those of Anniko et al [2] and Berglund and Ryugo [10] in human specimens, where all the spiral ganglion cells seemed to be stained. In contrast, other studies claim that NF-M and NF-L occur in type-2 spiral ganglion cells in rodents and the human embryo [7,8,[13][14][15], Whether or not this discrepancy is due to differences in mAbs or in species needs to be clarified.…”

“…The immunomorphology of the human inner ear has been studied extensively but mainly qualitatively during the past decade [1,2], Recent developments in computerassisted morphological techniques have focused on image analysis, which is intended to analyse and compare immunostained specimens providing quantitative and ob jective information.…”

“…Neurofilaments (NFs), which belong to the group of intermediate filaments, have been found in both the cen tral and the peripheral nervous system [3][4][5] including the stato-acoustic ganglion [1,2,[6][7][8][9][10][11][12][13][14][15]. Their functions are mechanical support and intracellular transport of sub stances and organelles along the axons.…”

Nuclear Factor κB Deficiency Is Associated with Auditory Nerve Degeneration and Increased Noise-Induced Hearing Loss

“…Synaptophysin is a well known marker for synaptic vesicles and is present in auditory nerve terminals in the organ of Corti. It can also act as a calcium-binding protein and is expressed in SGNs of the mammalian cochlea (Anniko et al, 1995;Rask-Andersen et al, 2000;Khalifa et al, 2003).…”

Opposite Actions of Brain-Derived Neurotrophic Factor and Neurotrophin-3 on Firing Features and Ion Channel Composition of Murine Spiral Ganglion Neurons

“…Electrophysiological (Mo and Davis, 1997a,b) and immunohistochemical (Romand et al, 1990;Lopez et al, 1995;Anniko et al, 1995;Salih et al, 1999;Adamson et al, 1999) studies have revealed an unexpected heterogeneity in the firing features and voltage-dependent ionic currents of spiral ganglion neurons that appear to vary as a function of position in the cochlea (Adamson et al, 1999;Davis et al, 2001). To determine whether these electrophysiological features are subject to extrinsic regulation, we evaluated the effects of neurotrophins on neuronal firing patterns and on ion channel distribution of postnatal spiral ganglion neurons placed in tissue culture.…”