Expression of myelin basic protein in the human auditory nerve - an immunohistochemical and comparative study

The aim of this study is to analyse the expression and distribution of myelin basic protein (MBP or Myelin A1 protein) in the human spiral ganglion and auditory nerve.

Cryostat sections were made from freshly fixed human cochlear specimens removed at surgery in patients with life-threatening petro-clival meningiomas compressing the brain stem. The sections were subjected to immunohistochemistry using antibodies against MBP, S-100 and Tubulin. The immunoreaction was documented using laser confocal microscopy.

Type I spiral ganglion nerve somata (SGN) were surrounded by so-called "satellite glial cells" (SGCs) that lacked expression of MBP consistent with earlier light and electron microscopic findings indicating that these cells are non-myelinating. S-100 labeling showed that the SGCs form a continuous network in the apical region.

The pattern of myelination in human spiral ganglion is different from that in other species' spiral ganglion. The striking differences in myelin outline should be investigated further in combination with its influence on signal coding and preservation properties in man.