Expression of myelin basic protein in the human auditory nerve—An immunohistochemical and comparative study Wei Liu a, * , Marja Bostro¨m a , Anders Kinnefors a , Fred Linthicum b,c , Helge Rask-Andersen a, ** a Dept. of Otolaryngology, Uppsala University Hospital, 75185 Uppsala, Sweden b House Ear Institute, Los Angeles, CA, USA c Otolaryngology/Head and Neck Surgery, The Keck School of Medicine of the University of Southern California, USA Received 25 October 2010; accepted 22 April 2011 Available online 20 May 2011 Abstract Objective: 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. Materials and methods: 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. Results: 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. Conclusions: 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. # 2011 Elsevier Ireland Ltd. All rights reserved. Keywords: Human auditory nerve; Spiral ganglion; Satellite glial cells; Myelin basic protein; S-100; Immunofluoresence 1. Introduction Human hearing rests on roughly 15,000 cochlear hair cells that convert mechanic vibrations into electric signals in approximately 30,000 neurons in the auditory nerve [1]. The neural perikarya are sited in the axis of the cochlea and they demonstrate a remarkable resistance to deterioration vital for the function of cochlear implants (CI). While it is widely accepted that spiral ganglion nerve (SGN) survival depends on the integrity of the organ of Corti (OC) [21], human perikarya can persist even without connection to it [2–5]. The reason for this circumstance is unidentified although it implies that neurons may achieve trophic supply from other sources such as central axons or adjoining satellite cells surrounding nerve somata. www.elsevier.com/locate/anl Auris Nasus Larynx 39 (2012) 18–24 Abbreviations: SGN, spiral ganglion neurons; SGC, satellite glial cells; SG, spiral ganglion; HSG, human spiral ganglion; Type II SGN, spiral ganglion neurons innervating outer hair cells. These cells have been referred to as ‘‘small ganglion cells’’ in human; Type I SGN, spiral ganglion neurons innervating inner hair cells; MBP (or Myelin A1 protein), myelin basic protein; SC, Schwann cell; OC, organ of Corti. * Corresponding author at: Department of Surgical Sciences, Section of Otolaryngology, Uppsala University Hospital, SE-75185 Uppsala, Sweden. Tel.: +46 18 6115456; fax: +46 18 500979. ** Corresponding author at: Department of Surgical Sciences, Section of Otolaryngology, Uppsala University Hospital, SE-75185 Uppsala, Sweden. Tel.: +46 18 6119445; fax: +46 18 500979. E-mail addresses: lwoo24@gmail.com (W. Liu), marja.bostrom@surgsci.uu.se (M. Bostro¨m), anders.kinnefors@akademiska.se (A. Kinnefors), FLinthicum@hei.org (F. Linthicum), helge.rask-andersen@akademiska.se (H. Rask-Andersen). 0385-8146/$ – see front matter # 2011 Elsevier Ireland Ltd. All rights reserved. doi:10.1016/j.anl.2011.04.007