title: Quantitative polarized light microscopy of unstained mammalian cochlear sections.
abstract: Hearing loss is the most common sensory deficit in the world, and most frequently it originates in the inner ear. Yet, the inner ear has been difficult to access for diagnosis because of its small size, delicate nature, complex three-dimensional anatomy, and encasement in the densest bone in the body. Evolving optical methods are promising to afford cellular diagnosis of pathologic changes in the inner ear. To appropriately interpret results from these emerging technologies, it is important to characterize optical properties of cochlear tissues. Here, we focus on that characterization using quantitative polarized light microscopy (qPLM) applied to unstained cochlear sections of the mouse, a common animal model of human hearing loss. We find that the most birefringent cochlear materials are collagen fibrils and myelin. Retardance of the otic capsule, the spiral ligament, and the basilar membrane are substantially higher than that of other cochlear structures. Retardance of the spiral ligament and the basilar membrane decrease from the cochlear base to the apex, compared with the more uniform retardance of other structures. The intricate structural details revealed by qPLM of unstained cochlear sections ex vivo strongly motivate future application of polarization-sensitive optical coherence tomography to human cochlea in vivo.
authors: Harvard Medical School, Department of Otology and Laryngology, 25 Shattuck Street, Boston, MA 02115, USA.
authors: Neil M
authors: NM
authors: Kalwani
authors: Cheng Ai
authors: CA
authors: Ong
authors: Andrew C
authors: AC
authors: Lysaght
authors: Simon J
authors: SJ
authors: Haward
authors: Gareth H
authors: GH
authors: McKinley
authors: Konstantina M
authors: KM
authors: Stankovic
mesh_terms: D000818:Animals; D001489:Basilar Membrane / Q000033:anatomy & histology / Q000378:metabolism; D001718:Birefringence; D003051:Cochlea / Q000033:anatomy & histology* / Q000378:metabolism* / Q000473:pathology; D003094:Collagen / Q000378:metabolism; D034381:Hearing Loss / Q000175:diagnosis / Q000378:metabolism / Q000473:pathology; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008808:Mice, Inbred CBA; D008859:Microscopy, Polarization / Q000379:methods*; D023421:Models, Animal; D009186:Myelin Sheath / Q000378:metabolism / Q000473:pathology; D055620:Optical Phenomena; D009925:Organ of Corti / Q000033:anatomy & histology / Q000378:metabolism; D055493:Spiral Ligament of Cochlea / Q000033:anatomy & histology / Q000378:metabolism; D013316:Stria Vascularis / Q000166:cytology / Q000378:metabolism
chemical_list: D003094:Collagen