Article

Electron microscopy of degenerative changes in the chick basilar papilla after gentamicin exposure

  1. Keiko Hirose1,†,
  2. Lesnick E. Westrum2,3,
  3. Dale E. Cunningham2,
  4. Edwin W Rubel1,2,3,*

Article first published online: 23 JAN 2004

DOI: 10.1002/cne.11046

Issue

Journal of Comparative Neurology

Journal of Comparative Neurology

Volume 470, Issue 2, pages 164–180, 1 March 2004

Additional Information

How to Cite

Hirose, K., Westrum, L. E., Cunningham, D. E. and Rubel, E. W. (2004), Electron microscopy of degenerative changes in the chick basilar papilla after gentamicin exposure. J. Comp. Neurol., 470: 164–180. doi: 10.1002/cne.11046

Author Information

  1. 1

    Department of Otolaryngology-Head and Neck Surgery, University of Washington, Seattle, Washington 98195

  2. 2

    Virginia Merrill Bloedel Hearing Research Center, University of Washington, Seattle, Washington 98195

  3. 3

    Department of Neurological Surgery, University of Washington, Seattle, Washington 98195

  1. †

    Departments of Neurosciences and of Otolaryngology and Communicative Disorders, Cleveland Clinic Foundation, 9500 Euclid Avenue, Cleveland, OH 44195

*Department of Otolaryngology-Head and Neck Surgery, University of Washington, Seattle, WA 98195

Publication History

  1. Issue published online: 23 JAN 2004
  2. Article first published online: 23 JAN 2004
  3. Manuscript Accepted: 27 OCT 2003
  4. Manuscript Revised: 16 SEP 2003
  5. Manuscript Received: 9 MAY 2003

Funded by

  • National Institute on Deafness and Other Communication Disorders. Grant Numbers: DC04661, DC02854
  • Oberkotter Foundation

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Keywords:

  • ototoxicity;
  • hearing loss;
  • inner ear;
  • cochlea

Abstract

We present a sequential study of the substructural alterations in the chick basilar papilla at the earliest signs of hair cell degeneration. Three-day posthatch chicks received a single injection of gentamicin (300 mg/kg) and were killed at 6, 8, 12, 15, 18, 21, and 24 hours after the injection. The basilar papillae were studied by conventional transmission electron microscopy. Examination was limited to the basal region, where all hair cells are eliminated by this treatment. As early as 8 hours and clearly by 12 hours, altered fine structure was seen in hair cells. Changes included rounding and swelling of the hair cells, condensation of nuclear chromatin, dissolution of ribosomes, dilatation of the mitochondria, and accumulation of inclusion bodies and lysosomes. By 15–18 hours, lysosomes increased and became denser, afferent terminals appeared swollen, and the first cell extrusion was seen. Efferents were unaffected, and supporting cells, though having inclusion bodies now, retained normal intercellular junctions. By 21–24 hours, large regions of complete hair cell loss were composed of expanded supporting cell processes with normal-appearing intercellular junctions and portions of extruded hair cells, partially attached to the supporting cell surface. These observations demonstrate that auditory hair cells undergo a rapid and controlled process of hair cell extrusion that allows preservation of the reticular lamina and minimal contamination of surrounding structures by intracytoplasmic contents of the damaged hair cells. J. Comp. Neurol. 470:164–180, 2004. © 2004 Wiley-Liss, Inc.

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