DOCSLIB.ORG

Reticular Lamina and Basilar Membrane Vibrations in Living Mouse Cochleae

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Reticular Lamina and Basilar Membrane Vibrations in Living Mouse Cochleae Reticular lamina and basilar membrane vibrations in living mouse cochleae Tianying Rena,1, Wenxuan Hea, and David Kempb aOregon Hearing Research Center, Department of Otolaryngology, Oregon Health & Science University, Portland, OR 97239; and bUniversity College London Ear Institute, University College London, London WC1E 6BT, United Kingdom Edited by Mario A. Ruggero, Northwestern University, Evanston, IL, and accepted by Editorial Board Member Peter L. Strick July 1, 2016 (received for review May 9, 2016) It is commonly believed that the exceptional sensitivity of mamma- (Fig. 1 A and B and Materials and Methods). The results from this lian hearing depends on outer hair cells which generate forces for study do not demonstrate the commonly expected cochlear local amplifying sound-induced basilar membrane vibrations, yet how feedback but instead indicate a global hydromechanical mecha- cellular forces amplify vibrations is poorly understood. In this study, nism for outer hair cells to enhance hearing sensitivity. by measuring subnanometer vibrations directly from the reticular lamina at the apical ends of outer hair cells and from the basilar Results membrane using a custom-built heterodyne low-coherence interfer- Vibrations of the Reticular Lamina and Basilar Membrane in Sensitive ometer, we demonstrate in living mouse cochleae that the sound- Cochleae. Vibrations of the reticular lamina and basilar membrane induced reticular lamina vibration is substantially larger than the measured from a sensitive cochlea are presented in Fig. 1 C–J. basilar membrane vibration not only at the best frequency but Below 50 dB sound pressure level (SPL) (0 dB SPL = 20 μPa), the surprisingly also at low frequencies. The phase relation of reticular basilar membrane vibration increased with frequency and reached lamina to basilar membrane vibration changes with frequency by up the maximum at ∼48 kHz (best frequency) and then decreased, to 180 degrees from ∼135 degrees at low frequencies to ∼-45 de- forming a sharp peak (Fig. 1C). The peak became broader and grees at the best frequency. The magnitude and phase differences shifted toward low frequencies as the sound level increased. The between reticular lamina and basilar membrane vibrations are ab- ratios of the basilar membrane displacement to the malleus dis- sent in postmortem cochleae. These results indicate that outer hair placement at low sound levels confirm the best frequency of NEUROSCIENCE cells do not amplify the basilar membrane vibration directly through ∼48 kHz (Fig. 1E). The peak ratio decreased from >100 to ∼3as a local feedback as commonly expected; instead, they actively vi- the sound level increased from 20 to 80 dB SPL, indicating ∼30-dB brate the reticular lamina over a broad frequency range. The outer nonlinear compression. The overlapping curves at frequencies hair cell-driven reticular lamina vibration collaboratively interacts below 35 kHz (Fig. 1E) indicate the linear growth at low fre- with the basilar membrane traveling wave primarily through the quencies. The basilar membrane vibration phase (referred to as the cochlear fluid, which boosts peak responses at the best-frequency malleus phase) decreased with frequency (Fig. 1G). Data in Fig. 1 location and consequently enhances hearing sensitivity and frequency C E selectivity. and demonstrate the high sensitivity, sharp tuning, and non- linearity of basilar membrane responses to ultrasonic sounds in the cochlea | outer hair cells | hearing | cochlear amplifier | interferometry living mouse cochlea, which are similar to previous measurements in squirrel monkeys (19), gerbils (20–23), chinchillas (17, 24, 25), guinea pigs (26–28), and mice (7, 29, 30). s the auditory sensory organ, the mammalian cochlea is able By contrast, the displacement of the reticular lamina vibration to detect soft sounds at levels as low as ∼20 μPa, equivalent to A (Fig. 1D) was substantially larger than that of the basilar mem- eardrum vibrations of <1-pm displacement (1), which is >100-fold brane vibration. At 20 dB SPL, reticular lamina vibrations were smaller than the diameter of a hydrogen atom. The cochlea’sre- the greatest approximately at the same frequency as the best markable sensitivity is commonly attributed to a micromechanical frequency of the basilar membrane (∼48 kHz). Notably, the peak feedback system, which amplifies soft sounds using forces gen- erated by outer hair cells (2–10). In addition to active bundle movements (2), mammalian outer hair cells are capable of Significance changing their lengths in response to electrical stimulation in vitro (11–14). This electromechanical force production is termed outer The remarkable sensitivity of mammalian hearing depends on hair cell electromotility or somatic motility, which is produced by auditory sensory outer hair cells, yet how these cells enhance the the membrane protein, prestin (15). Transgenic mice without hearing sensitivity remains unclear. By measuring subnanometer prestin or with altered prestin suffer from severe hearing loss vibrations directly from motile outer hair cells in living inner ear, (4, 16). Targeted inactivation of prestin over well-defined cochlear we demonstrate that outer hair cells do not directly amplify the segments dramatically reduces the traveling wave’speakresponse basilar membrane vibration by local feedback as commonly (17). Recent micromechanical measurements in sensitive living expected; instead, they actively vibrate the reticular lamina over a broad frequency range. The outer hair cell-driven reticular lamina mouse cochleae showed (18) that electrical stimulation of outer vibration interacts with the basilar membrane traveling wave hair cells induces vigorous vibrations of the reticular lamina at the through the cochlear fluid, resulting in maximal vibrations at the apical surfaces of the outer hair cells. Whereas this experiment best-frequency location, consequently enhancing hearing sensi- demonstrates that outer hair cells are capable of generating sub- tivity. This finding advances our knowledge of mammalian hear- stantial forces to vibrate cochlear microstructures in vivo, the lack ingandmayleadtostrategiesforrestoringhearinginpatients. of frequency selectivity of the electrically induced reticular lamina vibration, however, is inconsistent with the sharp tuning of the Author contributions: T.R. designed research; T.R. and W.H. performed research; T.R., W.H., basilar membrane vibration. Because electrical stimulation is not a and D.K. analyzed data; and T.R., W.H., and D.K. wrote the paper. natural stimulus of the auditory system, we here investigate how The authors declare no conflict of interest. acoustically induced reticular lamina vibrations interact with bas- This article is a PNAS Direct Submission. M.A.R. is a Guest Editor invited by the Editorial ilar membrane vibrations in sensitive living mouse cochleae, using Board. a custom-built scanning heterodyne low-coherence interferometer 1To whom correspondence should be addressed. Email: [email protected]. www.pnas.org/cgi/doi/10.1073/pnas.1607428113 PNAS Early Edition | 1of6 Downloaded by guest on September 29, 2021 nonlinear compression. Surprisingly, displacements of the reticular lamina at frequencies far below the best frequency were also ∼10- fold greater than those of the basilar membrane (Fig. 1D). Dis- placement ratios of the reticular lamina to the malleus in Fig. 1F show a peak magnitude of ∼1,000 at low sound levels, which is larger than that of the basilar membrane (Fig. 1E). With an in- crease in sound level from 20 to 80 dB SPL, the peak magnitude decreased by ∼45 dB for the reticular lamina vibration (Fig. 1F) and by ∼30 dB for the basilar membrane vibration (Fig. 1E). The phase responses of the reticular lamina (Fig. 1H) were similar to those of the basilar membrane (Fig. 1G). Ratios of the reticular lamina to basilar membrane displacement greater than one (Fig. 1I) confirm that the reticular lamina vi- brated more than the basilar membrane at all frequencies and sound levels. Near 48 kHz, 30-dB SPL tone-induced reticular lamina vibration was approximately sevenfold greater than that of the basilar membrane. This difference decreased with sound level and approached one at 80 dB SPL. At a given sound level, the magnitude ratio decreased with frequency up to ∼48 kHz. The magnitude ratio curves also shifted toward low frequencies with the sound level increase. Surprisingly, the largest-magnitude ratios occurred at frequencies far below the best frequency and at high sound levels, which likely resulted from the saturation near the best frequency. The phase difference of >90 degrees in Fig. 1J indicates that the reticular lamina and basilar membrane vibrated approximately in opposite directions at frequencies below 15 kHz. The lack of substantial phase difference near 48 kHz, however, demonstrates that the reticular lamina and the basilar membrane moved in the same direction at the best frequency. Vibrations of the Reticular Lamina and Basilar Membrane in Insensitive Cochleae. Under postmortem conditions, the basilar membrane and reticular lamina vibrations (blue lines in Fig. 2 A and B) showed decreased magnitude near the best frequency, peak shift toward low frequencies, and linear growth with the sound level. In contrast with the lack of substantial postmortem change in basilar membrane vibration at frequencies below 30 kHz in Fig. 2A,the reticular lamina displacements decreased by ∼10-fold (or 20 dB) over the same frequency range (Fig. 2B). These postmortem magnitude
Load more

Recommended publications
  • Vibration Hotspots Reveal Longitudinal Funneling of Sound-Evoked Motion in the Mammalian Cochlea
    ARTICLE DOI: 10.1038/s41467-018-05483-z OPEN Vibration hotspots reveal longitudinal funneling of sound-evoked motion in the mammalian cochlea Nigel P. Cooper 1, Anna Vavakou1 & Marcel van der Heijden 1 The micromechanical mechanisms that underpin tuning and dynamic range compression in the mammalian inner ear are fundamental to hearing, but poorly understood. Here, we present new, high-resolution optical measurements that directly map sound-evoked vibra- 1234567890():,; tions on to anatomical structures in the intact, living gerbil cochlea. The largest vibrations occur in a tightly delineated hotspot centering near the interface between the Deiters’ and outer hair cells. Hotspot vibrations are less sharply tuned, but more nonlinear, than basilar membrane vibrations, and behave non-monotonically (exhibiting hyper-compression) near their characteristic frequency. Amplitude and phase differences between hotspot and basilar membrane responses depend on both frequency and measurement angle, and indicate that hotspot vibrations involve longitudinal motion. We hypothesize that structural coupling between the Deiters’ and outer hair cells funnels sound-evoked motion into the hotspot region, under the control of the outer hair cells, to optimize cochlear tuning and compression. 1 Department of Neuroscience, Erasmus MC, Room Ee 1285, P.O. Box 2040, 3000 CA Rotterdam, The Netherlands. Correspondence and requests for materials should be addressed to M.v.d.H. (email: [email protected]) NATURE COMMUNICATIONS | (2018) 9:3054 | DOI: 10.1038/s41467-018-05483-z
    [Show full text]
  • ANATOMY of EAR Basic Ear Anatomy
    ANATOMY OF EAR Basic Ear Anatomy • Expected outcomes • To understand the hearing mechanism • To be able to identify the structures of the ear Development of Ear 1. Pinna develops from 1st & 2nd Branchial arch (Hillocks of His). Starts at 6 Weeks & is complete by 20 weeks. 2. E.A.M. develops from dorsal end of 1st branchial arch starting at 6-8 weeks and is complete by 28 weeks. 3. Middle Ear development —Malleus & Incus develop between 6-8 weeks from 1st & 2nd branchial arch. Branchial arches & Development of Ear Dev. contd---- • T.M at 28 weeks from all 3 germinal layers . • Foot plate of stapes develops from otic capsule b/w 6- 8 weeks. • Inner ear develops from otic capsule starting at 5 weeks & is complete by 25 weeks. • Development of external/middle/inner ear is independent of each other. Development of ear External Ear • It consists of - Pinna and External auditory meatus. Pinna • It is made up of fibro elastic cartilage covered by skin and connected to the surrounding parts by ligaments and muscles. • Various landmarks on the pinna are helix, antihelix, lobule, tragus, concha, scaphoid fossa and triangular fossa • Pinna has two surfaces i.e. medial or cranial surface and a lateral surface . • Cymba concha lies between crus helix and crus antihelix. It is an important landmark for mastoid antrum. Anatomy of external ear • Landmarks of pinna Anatomy of external ear • Bat-Ear is the most common congenital anomaly of pinna in which antihelix has not developed and excessive conchal cartilage is present. • Corrections of Pinna defects are done at 6 years of age.
    [Show full text]
  • Ultrastructural Analysis and ABR Alterations in the Cochlear Hair-Cells Following Aminoglycosides Administration in Guinea Pig
    Global Journal of Otolaryngology ISSN 2474-7556 Research Article Glob J Otolaryngol Volume 15 Issue 4 - May 2018 Copyright © All rights are reserved by Mohammed A Akeel DOI: 10.19080/GJO.2018.15.555916 Ultrastructural Analysis and ABR Alterations in the Cochlear Hair-cells Following Aminoglycosides Administration in Guinea Pig Mohammed A Akeel* Department of Anatomy, Faculty of Medicine, Jazan University, Jazan, Kingdom of Saudi Arabia Submission: April 18, 2018; Published: May 08, 2018 *Corresponding author: Mohammed A Akeel, Faculty of Medicine, Jazan University, P.O.Box 114, Jazan, Kingdom of Saudi Arabia. Tel: ; Email: Abstract Aims: since their introduction in the 1940. The aim of the present work was to characterize ultrastructural alterations of the sensory hair-cell following different aminoglycosides Aminoglycosides administration, (AG) antibiotics intratympanic were the first VS ototoxic intraperitoneal agents to and highlight to correlate the problem them with of drug-induced auditory brainstem hearing responses and vestibular (ABR). loss, Methods: streptomycin, gentamycin, or netilmicin; respectively, via the peritoneal route. The next four groups received similar treatment via trans- tympanic route. A Thetotal treatment of 48 adult was guinea administered pigs were dividedfor seven into consecutive 8 groups; sixdays. animals On day in 10,each ABR group. was The utilized first fourfor hearing groups receivedevaluation saline and (control),scanning electron microscopy (SEM) examination of the sensory organs was used for morphological study. Results: Streptomycin produced the most severe morphological changes and a higher elevation of ABR thresholds, followed, in order, by gentamycin and netilmicin. Netilmicin ototoxicity observed in both systemic and transtympanic routes was low because of lesser penetration into the inner ear or/ and lower intrinsic toxicity.
    [Show full text]
  • The Tectorial Membrane of the Rat'
    The Tectorial Membrane of the Rat’ MURIEL D. ROSS Department of Anatomy, The University of Michigan, Ann Arbor, Michigan 48104 ABSTRACT Histochemical, x-ray analytical and scanning and transmission electron microscopical procedures have been utilized to determine the chemical nature, physical appearance and attachments of the tectorial membrane in nor- mal rats and to correlate these results with biochemical data on protein-carbo- hydrate complexes. Additionally, pertinent histochemical and ultrastructural findings in chemically sympathectomized rats are considered. The results indi- cate that the tectorial membrane is a viscous, complex, colloid of glycoprotein( s) possessing some oriented molecules and an ionic composition different from either endolymph or perilymph. It is attached to the reticular laminar surface of the organ of Corti and to the tips of the outer hair cells; it is attached to and encloses the hairs of the inner hair cells. A fluid compartment may exist within the limbs of the “W’formed by the hairs on each outer hair cell surface. Present biochemical concepts of viscous glycoproteins suggest that they are polyelectro- lytes interacting physically to form complex networks. They possess character- istics making them important in fluid and ion transport. Furthermore, the macro- molecular configuration assumed by such polyelectrolytes is unstable and subject to change from stress or shifts in pH or ions. Thus, the attachments of the tec- torial membrane to the hair cells may play an important role in the transduction process at the molecular level. The present investigation is an out- of the tectorial membrane remain matters growth of a prior study of the effects of of dispute.
    [Show full text]
  • Otto Friedrich Karl Deiters (1834–1863)
    REVIEW Otto Friedrich Karl Deiters (1834–1863) Vera S. Deiters,1 and R.W. Guillery2* 1Am Krausberg 8, 52351, Duren,€ Germany 2MRC Anatomical Neuropharmacology Unit, Mansfield Road, Oxford, OX1 3TH, United Kingdom ABSTRACT However, first his father and then his younger brother Otto Deiters, for whom the lateral vestibular nucleus died, leaving him and his older brother responsible for and the supporting cells of the outer auditory hair cells a suddenly impecunious family as he failed to gain aca- were named, died in 1863 aged 29. He taught in the demic promotion. Otto died of typhus two years after Bonn Anatomy Department, had an appointment in the his younger brother’s death, leaving his greatest scien- University Clinic, and ran a small private practice. He tific achievement to be published posthumously. He published articles on the cell theory, the structure and showed that most nerve cells have a single axon and development of muscle fibers, the inner ear, leukaemia, several dendrites; he recognized the possibility that and scarlet fever. He was the second of five surviving nerve cells might be functionally polarized and pro- children in an academic family whose private corre- duced the first illustrations of synaptic inputs to den- spondence revealed him to be a young man with lim- drites from what he termed a second system of nerve ited social skills and high ambitions to complete a fibers. J. Comp. Neurol. 521:1929–1953, 2013. deeply original study of the brainstem and spinal cord. VC 2013 Wiley Periodicals, Inc. INDEXING TERMS: history; Deiters cells; Deiters nucleus; axons; dendrites; synapses Otto Deiters died on December 5, 1863, 150 years Charite (Fig.
    [Show full text]
  • Inner Ear Defects and Hearing Loss in Mice Lacking the Collagen Receptor
    Laboratory Investigation (2008) 88, 27–37 & 2008 USCAP, Inc All rights reserved 0023-6837/08 $30.00 Inner ear defects and hearing loss in mice lacking the collagen receptor DDR1 Angela M Meyer zum Gottesberge1, Oliver Gross2, Ursula Becker-Lendzian1, Thomas Massing1 and Wolfgang F Vogel3 Discoidin domain receptor 1 (DDR1) is a tyrosine kinase receptor that is activated by native collagen. The physiological functions of DDR1 include matrix homeostasis and cell growth, adhesion, branching, and migration, but the specific role of DDR1 in the development and function of the inner ear has not been analyzed. Here, we show that deletion of the DDR1 gene in mouse is associated with a severe decrease in auditory function and substantial structural alterations in the inner ear. Immunohistochemical analysis demonstrated DDR1 expression in several locations in the cochlea, mostly associated with basement membrane and fibrillar collagens; in particular in basal cells of the stria vascularis, type III fibrocytes, and cells lining the basilar membrane of the organ of Corti. In the stria vascularis, loss of DDR1 function resulted in altered morphology of the basal cells and accumulation of electron-dense matrix within the strial epithelial layer in conjunction with a focal and progressive deterioration of strial cells. Cell types in proximity to the basilar membrane, such as Claudius’, inner and outer sulcus cells, also showed marked ultrastructural alterations. Changes in the organ of Corti, such as deterioration of the supporting cells, specifically the outer hair cells, Deiters’, Hensen’s and bordering cells, are likely to interfere with mechanical properties of the organ and may be responsible for the hearing loss observed in DDR1-null mice.
    [Show full text]
  • Supporting Cell Proliferation After Hair Cell Injury in Mature Guinea Pig Cochlea in Vivo
    Cell Tissue Res (2006) 325: 23–31 DOI 10.1007/s00441-006-0157-9 REGULAR ARTICLE Tatsuya Yamasoba . Kenji Kondo Supporting cell proliferation after hair cell injury in mature guinea pig cochlea in vivo Received: 4 October 2005 / Accepted: 4 January 2006 / Published online: 9 March 2006 # Springer-Verlag 2006 Abstract In cold-blooded animals, lost sensory hair cells competence to re-enter the cell cycle and proliferate after can be replaced via a process of regenerative cell prolif- hair cell injury, and that they can survive at least for eration of epithelial supporting cells. In contrast, in 1 month. mammalian cochlea, receptor (hair) cells are believed to be produced only during embryogenesis; after maturity, Keywords Cochlea . BrdU . p27 . Deiters cell . Hair cell . sensory or supporting cell proliferation or regeneration are Regeneration . Guinea pig thought to occur neither under normal conditions nor after trauma. Using bromodeoxyuridine (BrdU) as a prolifera- tion marker, we have assessed cell proliferation activity in Introduction the mature organ of Corti in the cochlea of young guinea pigs following severe damage to the outer hair cells Sensory receptors (hair cells) in the mammalian ear are induced by kanamycin sulfate and ethacrynic acid. located in the cochlear organ of Corti (OC) and in the Although limited, we have found BrdU-labeled nuclei in vestibular sensory epithelia of the saccular macula, the the regions of Deiters cells when BrdU is given for 3 days utricular macula, and the cristae of the three semicircular or longer. When BrdU is given for 10 days, at least one canals. Two types of hair cells have been found in the OC: labeled nucleus can be observed in the organ of Corti in the inner (IHCs) and outer (OHCs) hair cells.
    [Show full text]
  • Postnatal Development of the Subcellular Structures and Purinergic Signaling of Deiters’ Cells Along the Tonotopic Axis of the Cochlea
    cells Article Postnatal Development of the Subcellular Structures and Purinergic Signaling of Deiters’ Cells along the Tonotopic Axis of the Cochlea Eszter Berekméri 1,2, Ádám Fekete 3,László Köles 1 and Tibor Zelles 1,4,* 1 Department of Pharmacology and Pharmacotherapy, Semmelweis University, Nagyvárad tér 4., 1089 Budapest, Hungary; [email protected] (E.B.); [email protected] (L.K.) 2 Department of Ecology, University of Veterinary Medicine, Rottenbiller u. 50., 1077 Budapest, Hungary 3 Program in Neurosciences and Mental Health, The Hospital for Sick Children, 555 University Ave, Toronto, ON M5G 1X8, Canada; [email protected] 4 Department of Pharmacology, Institute of Experimental Medicine, Hungarian Academy of Sciences, Szigony u. 43., 1083 Budapest, Hungary * Correspondence: [email protected]; Tel.: +36-1-210-2930 (ext. 56297); Fax: +36-1-210-4412 Received: 3 September 2019; Accepted: 15 October 2019; Published: 17 October 2019 Abstract: Exploring the development of the hearing organ helps in the understanding of hearing and hearing impairments and it promotes the development of the regenerative approaches-based therapeutic efforts. The role of supporting cells in the development of the organ of Corti is much less elucidated than that of the cochlear sensory receptor cells. The use of our recently published method of single-cell electroporation loading of a fluorescent Ca2+ probe in the mouse hemicochlea preparation provided an appropriate means to investigate the Deiters’ cells at the subcellular level in two different cochlear turns (apical, middle). Deiters’ cell’s soma and process elongated, and the process became slimmer by maturation without tonotopic preference.
    [Show full text]
  • Structural Aspects of Slow Mechanical Adaptation in the Vertebrate Cochlea
    International Journal of Comparative Psychology, 2006, 19, 62-82. Copyright 2006 by the International Society for Comparative Psychology Structural Aspects of Slow Mechanical Adaptation in the Vertebrate Cochlea Olga Ganeshina and Misha Vorobyev University of Queensland, Australia Anatomical and experimental data suggesting a slow adaptation of cochlear mechanics are summa- rized and discussed. All groups of terrestrial vertebrates, possessing advanced hearing—mammals, Archosauria (birds and crocodiles) and lizards—developed intrinsic cochlear specializations, which may adjust cochlear mechanics and therefore adapt hearing to different acoustic environments, or protect the cochlea from excessive mechanical stimuli. Mammalian outer hair cells, several types of supporting cells, hyaline and homogene in birds and crocodiles, and putative contractile cells of the cochlear lateral wall in mammals and in geckos may provide structural basis for the slow mechanical adaptation. Independent appearance of these specializations in animals that developed different co- chlear designs may indicate that the maintainence of “mechanical homeostasis” is a common re- quirement for the highly organized hearing organ. Mechano-electric transduction in the vertebrate hearing organs is mediated by mechano-sensitive channels located on the hair cell stereocilia, whose deflec- tion produces an adequate physiological signal. The full dynamic range of the stereocilium transducer is narrow, since it covers approximately 2 angular degrees of hair displacement, or 100 nm of a total excursion at the tip of the hair bundle (Furness et al., 1997; Kros, Lennan, & Richardson, 1995; see Fettiplace & Ricci, 2003). Therefore, precise control of the mechanical input is required to keep the auditory hair cells within their operating range (Fettiplace & Ricci, 2003).
    [Show full text]
  • The Cochlea of the Dolphin, Tursiops Truncatus: General Morphology* (Organ of Corti/Ear/Light Microscopy) ERNEST GLEN WEVER, JAMES G
    Proc. Nat. Acad. Sci. USA Vol. 68, No. 10, pp. 2381-2385, October 1971 The Cochlea of the Dolphin, Tursiops truncatus: General Morphology* (organ of Corti/ear/light microscopy) ERNEST GLEN WEVER, JAMES G. McCORMICKt, JERRY PALIN, AND SAM H. RIDGWAYT Department of Psychology, Auditory Research Laboratories, Princeton University, Princeton, New Jersey 08540 Contributed by Ernest Glen Wever, July 16, 1971 ABSTRACT The anatomy of the cochlea of the dolphin chloride. The ears were removed, further fixed by immersion Tursiops truncatus was studied in a number of specimens for 10 days, then held in 10% formol for final processing. after fixation by vital perfusion, celloidin embedding, and serial sectioning. The results reveal the general structural The dolphin ear is a formidable object for histology, as relations and cellular detail up to the limits of light Kolmer remarked earlier (3). We used several specimens and microscopy. A description is given of the variations of more than a year for the necessary adaptations of our usual structure along the course of the cochlea, in which there methods. In our final procedure, we decalcified the tissues are many departures from the typical mammalian form, especially in the compact quality of the tissues and the in 0.5% nitric acid in 10% formol, changed the solution 60 sturdiness of its elements. Apparently these features times over a period of 3 months, dehydrated the tissues in represent an adaptation of the cetacean ear to the recep- a series of alcohols ranging from 20 to 100%, in 10% steps, tion of high-frequency sounds. over a period of 1 month, embedded the tissues in celloidin in four steps from 4 to 16% over a period of 6 months, and Though many have studied the gross anatomy of the cetacean finally hardened them in chloroform and alcohol.
    [Show full text]
  • Scanning Electron Microscopy of the Celloidin-Embedded Inner Ear Sections
    Scanning Microscopy Volume 4 Number 4 Article 11 9-17-1990 Scanning Electron Microscopy of the Celloidin-Embedded Inner Ear Sections Kunihiro Mizuta Hamamatsu University Tomoyuki Hoshino Hamamatsu University Hirofumi Morita Hamamatsu University Follow this and additional works at: https://digitalcommons.usu.edu/microscopy Part of the Biology Commons Recommended Citation Mizuta, Kunihiro; Hoshino, Tomoyuki; and Morita, Hirofumi (1990) "Scanning Electron Microscopy of the Celloidin-Embedded Inner Ear Sections," Scanning Microscopy: Vol. 4 : No. 4 , Article 11. Available at: https://digitalcommons.usu.edu/microscopy/vol4/iss4/11 This Article is brought to you for free and open access by the Western Dairy Center at DigitalCommons@USU. It has been accepted for inclusion in Scanning Microscopy by an authorized administrator of DigitalCommons@USU. For more information, please contact [email protected]. Scanning Microscopy, Vol. 4, No. 4, 1990 (Pages 967-973) 0891-7035/90$3.00+.00 Scanning Microscopy International, Chicago (AMF O'Hare), IL 60666 USA SCANNING ELECTRON MICROSCOPY OF THE CELLOIDIN-EMBEDDED INNER EAR SECTIONS Kunihiro Mizuta*, Tomoyuki Hoshino , Hirofumi Morita Department of Otolaryngology, Hamamatsu University School of Medicine Hamamatsu, Japan (Received for publication April 15, 1990, and in revised form September 17 , 1990) Abstract Introduction The nerve fibers running inside the organ The surface preparation technique has of Corti were studied in cats by scanning usually been used to observe Corti's tunnel or electron microscopy (SEM) . The fixed temporal Nuel's space with the scanning electron micro­ bones were decalcified and embedded in celloidin scope (SEM). Several photomicrographs obtained according to the conventional method. Thick with this technique in the guinea pig (Wright serial sections (100-150 µm) were cut parallel to and Preston , 1975.
    [Show full text]
  • Dynamic Patterns of Neurotrophin 3 Expression in the Postnatal Mouse Inner Ear
    THE JOURNAL OF COMPARATIVE NEUROLOGY 501:30–37 (2007) Dynamic Patterns of Neurotrophin 3 Expression in the Postnatal Mouse Inner Ear MITSURU SUGAWARA,1,2,3 JOSHUA C. MURTIE,1 KONSTANTINA M. STANKOVIC,1,2 M. CHARLES LIBERMAN,2 AND GABRIEL CORFAS1* 1Neurobiology Program, Children’s Hospital and Department of Neurology, Harvard Medical School, Boston, Massachusetts 02115 2Department of Otology and Laryngology, Harvard Medical School and Eaton-Peabody Laboratory, Massachusetts Eye and Ear Infirmary, Boston, Massachusetts 02114-3096 3Department of Otolaryngology, Head and Neck Surgery, Tohoku University Graduate School of Medicine, Sendai, Japan 980-8574 ABSTRACT Recent studies indicate that neurotrophin 3 (NT3) may be important for the maintenance and function of the adult inner ear, but the pattern of postnatal NT3 expression in this organ has not been characterized. We used a reporter mouse in which cells expressing NT3 also express ␤-galactosidase, allowing for their histochemical visualization, to determine the pattern of NT3 expression in cochlear and vestibular organs. We analyzed animals from birth (P0) to adult (P135). At P0, NT3 was strongly expressed in supporting cells and hair cells of all vestibular and cochlear sense organs, Reissner’s membrane, saccular membrane, and the dark cells adjacent to canal organs. With increasing age, staining disappeared in most cell types but remained rela- tively high in inner hair cells (IHCs) and to a lesser extent in IHC supporting cells. In the cochlea, by P0 there is a longitudinal gradient (apex Ͼ base) that persists into adulthood. In vestibular maculae, staining gradients are: striolar Ͼ extrastriolar regions and supporting cells Ͼ hair cells.
    [Show full text]