Central trajectories of type II spiral ganglion neurons

Authors

  • M. C. Brown,

    1. Departments of Physiology and Otolaryngology, Harvard Medical School, Boston, Massachusetts 02115
    2. Eaton-Peabody Laboratory, Massachusetts Eye and Ear Infirmary, Boston, Massachusetts 02114
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  • A. M. Berglund,

    1. Department of Anatomy and Cellular Biology, Harvard Medical School, Boston, Massachusetts 02115
    2. Eaton-Peabody Laboratory, Massachusetts Eye and Ear Infirmary, Boston, Massachusetts 02114
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  • N. Y. S. Kiang,

    1. Departments of Physiology and Otolaryngology, Harvard Medical School, Boston, Massachusetts 02115
    2. Department of Brain and Cognitive Sciences, Whittaker College, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139
    3. Neurology Service, Massachusetts General Hospital, Boston, Massachusetts 02114
    4. Eaton-Peabody Laboratory, Massachusetts Eye and Ear Infirmary, Boston, Massachusetts 02114
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  • D. K. Ryugo

    1. Department of Anatomy and Cellular Biology, Harvard Medical School, Boston, Massachusetts 02115
    2. Center for Hearing Sciences, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205
    3. Eaton-Peabody Laboratory, Massachusetts Eye and Ear Infirmary, Boston, Massachusetts 02114
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Abstract

Previous attempts to trace the central pathways of the thin axons from type II spiral ganglion neurons have been hampered by technical difficulties such as fading of the reaction product as distance increases from the injection site (Ryugo et al.: Soc. Neurosci. Abstr. 12:779, '86; Brown: J. Comp. Neurol. 260:591–604, '87). By using small rodents (gerbils and mice), which have short auditory nerves, we have succeeded in filling the entire central axon and terminals of type II neurons after peripheral injections of horseradish peroxidase. The general course of the type II fibers within the auditory nerve and cochlear nucleus is similar to that of type I fibers except that terminals from type II neurons are often found in regions of the cochlear nucleus that have high densities of granule cells.

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