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The pre- and post-somatic segments of the human type I spiral ganglion neurons--structural and functional considerations related to cochlear implantation.

Liu W, Edin F, Atturo F, Rieger G, Löwenheim H, Senn P, Blumer M, Schrott-Fischer A, Rask-Andersen H, Glueckert R - Neuroscience (2014)

Bottom Line: These segments were found surrounded by non-myelinated Schwann cells (NMSCs) showing strong intracellular expression of laminin-β2/collagen IV.Their BMs express laminin-β2/collagen IV and reaches the BM of the sensory epithelium at the habenula perforata.We speculate that the NMSCs protect SGNs from further degeneration following dendrite loss.

View Article: PubMed Central - PubMed

Affiliation: Department of Surgical Sciences, Head and Neck Surgery, Section of Otolaryngology, Uppsala University Hospital, SE-751 85 Uppsala, Sweden; Department of Otolaryngology, Uppsala University Hospital, SE-751 85 Uppsala, Sweden. Electronic address: lwoo24@gmail.com.

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TEM of SGNs in a noise-damaged area 10–13 mm from the round window corresponding to the 4–6-kHz region. (A) Type I SGN with accumulation of intracytoplasmic inclusion bodies in the distal pole. AIS, axonal initial segment. Inset shows corresponding region at low magnification. Arrows indicate central direction. (B) Type I SGN with accumulation of inclusion bodies in the SGC in the distal pole. Inset shows framed area in higher magnification. A thin rim of myelin can be seen. (C) Foliated SGCs surrounding the distal pole of a SGN. Basement membrane (BM) is double-layered. Inset shows a gap junction between SGCs. SGC, satellite glial cell. (D) SGCs showing membrane specializations surround two SGNs. Framed area is magnified in F. (E) Foliated SGCs at the distal pole of a SGN. (F) Membrane specializations between two SGNs.
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f0035: TEM of SGNs in a noise-damaged area 10–13 mm from the round window corresponding to the 4–6-kHz region. (A) Type I SGN with accumulation of intracytoplasmic inclusion bodies in the distal pole. AIS, axonal initial segment. Inset shows corresponding region at low magnification. Arrows indicate central direction. (B) Type I SGN with accumulation of inclusion bodies in the SGC in the distal pole. Inset shows framed area in higher magnification. A thin rim of myelin can be seen. (C) Foliated SGCs surrounding the distal pole of a SGN. Basement membrane (BM) is double-layered. Inset shows a gap junction between SGCs. SGC, satellite glial cell. (D) SGCs showing membrane specializations surround two SGNs. Framed area is magnified in F. (E) Foliated SGCs at the distal pole of a SGN. (F) Membrane specializations between two SGNs.

Mentions: At the circumscribed lesion approx. 10 mm from the round window extending to about 13 mm the dominant pathological feature was the loss of outer hair cells. The degradation of inner hair cells was less severe with a 45% loss of myelinated nerve fibers at the osseous spiral lamina (Rask-Andersen et al., 2000a,b). The number of dendrites in Rosenthal’s canal was greatly reduced and only few SGNs with a peripheral process were observed (Figs.5B and 6B). 3D-reconstructions of SGNs from the patient with NIHL showed histological verified monopolar type I SGNs in 68.5% of totally 249 reconstructed SGNs. Arbitrary colored SGNs in Rosenthal’s canal from the affected basal turn is shown in Fig. 5B. At TEM many neural and satellite cell bodies displayed remarkable amount of intracytoplasmic inclusion bodies. In one cell these bodies accumulated in the distal pole of the cell (Fig. 6A). Another type I cell showed a thin layer of myelin (Fig. 6B). The satellite cells covering the peripheral pole of the SGN appeared more folded than usual and the BM was often multi- or double-layered (Fig. 6C, E). There were also signs of unusual cell body interaction. Cell surfaces of SGCs showed specializations with mirrored rugosities outlined by a BM (Fig. 6D, F). Gap junctions could be observed between different SGCs (Fig. 7C, inset).


The pre- and post-somatic segments of the human type I spiral ganglion neurons--structural and functional considerations related to cochlear implantation.

Liu W, Edin F, Atturo F, Rieger G, Löwenheim H, Senn P, Blumer M, Schrott-Fischer A, Rask-Andersen H, Glueckert R - Neuroscience (2014)

TEM of SGNs in a noise-damaged area 10–13 mm from the round window corresponding to the 4–6-kHz region. (A) Type I SGN with accumulation of intracytoplasmic inclusion bodies in the distal pole. AIS, axonal initial segment. Inset shows corresponding region at low magnification. Arrows indicate central direction. (B) Type I SGN with accumulation of inclusion bodies in the SGC in the distal pole. Inset shows framed area in higher magnification. A thin rim of myelin can be seen. (C) Foliated SGCs surrounding the distal pole of a SGN. Basement membrane (BM) is double-layered. Inset shows a gap junction between SGCs. SGC, satellite glial cell. (D) SGCs showing membrane specializations surround two SGNs. Framed area is magnified in F. (E) Foliated SGCs at the distal pole of a SGN. (F) Membrane specializations between two SGNs.
© Copyright Policy - CC BY-NC-ND
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4300406&req=5

f0035: TEM of SGNs in a noise-damaged area 10–13 mm from the round window corresponding to the 4–6-kHz region. (A) Type I SGN with accumulation of intracytoplasmic inclusion bodies in the distal pole. AIS, axonal initial segment. Inset shows corresponding region at low magnification. Arrows indicate central direction. (B) Type I SGN with accumulation of inclusion bodies in the SGC in the distal pole. Inset shows framed area in higher magnification. A thin rim of myelin can be seen. (C) Foliated SGCs surrounding the distal pole of a SGN. Basement membrane (BM) is double-layered. Inset shows a gap junction between SGCs. SGC, satellite glial cell. (D) SGCs showing membrane specializations surround two SGNs. Framed area is magnified in F. (E) Foliated SGCs at the distal pole of a SGN. (F) Membrane specializations between two SGNs.
Mentions: At the circumscribed lesion approx. 10 mm from the round window extending to about 13 mm the dominant pathological feature was the loss of outer hair cells. The degradation of inner hair cells was less severe with a 45% loss of myelinated nerve fibers at the osseous spiral lamina (Rask-Andersen et al., 2000a,b). The number of dendrites in Rosenthal’s canal was greatly reduced and only few SGNs with a peripheral process were observed (Figs.5B and 6B). 3D-reconstructions of SGNs from the patient with NIHL showed histological verified monopolar type I SGNs in 68.5% of totally 249 reconstructed SGNs. Arbitrary colored SGNs in Rosenthal’s canal from the affected basal turn is shown in Fig. 5B. At TEM many neural and satellite cell bodies displayed remarkable amount of intracytoplasmic inclusion bodies. In one cell these bodies accumulated in the distal pole of the cell (Fig. 6A). Another type I cell showed a thin layer of myelin (Fig. 6B). The satellite cells covering the peripheral pole of the SGN appeared more folded than usual and the BM was often multi- or double-layered (Fig. 6C, E). There were also signs of unusual cell body interaction. Cell surfaces of SGCs showed specializations with mirrored rugosities outlined by a BM (Fig. 6D, F). Gap junctions could be observed between different SGCs (Fig. 7C, inset).

Bottom Line: These segments were found surrounded by non-myelinated Schwann cells (NMSCs) showing strong intracellular expression of laminin-β2/collagen IV.Their BMs express laminin-β2/collagen IV and reaches the BM of the sensory epithelium at the habenula perforata.We speculate that the NMSCs protect SGNs from further degeneration following dendrite loss.

View Article: PubMed Central - PubMed

Affiliation: Department of Surgical Sciences, Head and Neck Surgery, Section of Otolaryngology, Uppsala University Hospital, SE-751 85 Uppsala, Sweden; Department of Otolaryngology, Uppsala University Hospital, SE-751 85 Uppsala, Sweden. Electronic address: lwoo24@gmail.com.

Show MeSH
Related in: MedlinePlus