DOCSLIB.ORG

The Cochlea of the Dolphin, Tursiops Truncatus: General Morphology* (Organ of Corti/Ear/Light Microscopy) ERNEST GLEN WEVER, JAMES G

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read 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. of the cochlea little 80% ear (1), the detailed structure has received We determined the proper orientation for sectioning by attention. Boenninghaus (2) examined several specimens of preparing skulls with the ear bones in place, and in two the Phocaena communis, and observed the general form of preparations the petrous bone was carefully ground away to Kolmer studied a young membranous labyrinth. (3) specimen expose the cochlear turns. Sections were cut at 30 usually a few after and was able to Am, of Phocaena obtained hours death, in a plane parallel to the cochlear axis, either approximately make out of the cellular structures. He identified the many vertical to the head, as shown in Fig. 1, or at right angles to of the elements of the organ kinds epithelial cells, supporting this position. One specimen was sectioned in a plane perpen- of Corti, and the hair cells, and pointed out especially the the which dicular to the cochlear axis. great size of cells of Claudius, be characterized as All sections through the ear were stained and mounted. the largest epithelial cells known in mammals. Two other re- For some of the series, we used Pollak's trichrome stain and for ports are mentioned in the references§ (4¶1). others a combination of hematoxylin, azocarmine, and orange METHOD G. Our study was performed on specimens of the bottlenosed dolphin, Tursiops truncatus Montagu, that had been used in an electrophysiological investigation of sound conduction (5). At the end of the tests on these ears, the anesthetized animals were perfused for histological examination. The blood was flushed out through a cannula in the dorsal aorta with about 40 liters of physiological saline, and then the tissues were fixed with 120 liters or more of a mixture of potassium dichromate, sodium sulfate, formaldehyde, and (sometimes) mercuric * This is the first of a series of articles on the cochlea of the dolphin, Tursiops truncatus. t Present address, Section of Otolaryngology, Bowman-Gray School of Medicine, Winston-Salem, N.C. $ Naval Undersea Research and Development Center, San Diego, Calif. § Bloome, K., The delphinid auditory apparatus, Parts I and II. Unpublished; seen in manuscript. An electron microscope study of tissues from freshly killed dolphins. Special attention is given to the microvilli on many of the sensory cells. ¶ In Russian, translated by Joint Publications Research Service. The description of cochlear structures is brief and FIG. 1. A posterior view of a skull of Tursiops truncatus, show- indicates close similarities to terrestrial mammals. ing the vertical planes for right and left cochleas. 2381 Downloaded by guest on September 29, 2021 2382 Physiology: Wever et al. Proc. Nat. Acad. Sci. USA 68 (1971) Of 25 ears treated in the preliminary and final procedures, The large cochlear nerve is seen as it sends its bundles into good to excellent results were obtained in 7, and in 6 others the ganglionic masses in the different turns. The ganglia are the series were useful for such purposes as observations of the only partially enclosed in the bone of the modiolus in basal and width of the basilar membrane and the distribution of gan- lower apical regions, and in the upper apical region the glion cells. ganglion lies almost free in the scala tympani. The first step in the study of these ears was the graphic re- This picture indicates also the varying size of the cochlear construction of the cochlear spiral by Guild's method (6). structures from lower basal to upper apical regions. We see in The junctions between the inner and outer pillar cells were this progression a decrease in the cross-sectional area of the located for every cochlear turn cut tangentially, and these scala tympani, an increase in the area of the scala vestibuli, points were laid out on a graph along a chosen axis. Semicircles the greatly diminishing mass of the external spiral ligament, were drawn from centers on the axis to connect the appropriate a considerable increase in the width of the basilar membrane, points, yielding a good approximation to a spiral except for the and a moderate increase in the size of the tectorial membrane. two end portions. The end points were located and measure- ments were made between them and cochlear turns already Cochlear structure outlined, from which the extensions were drawn in. The result The features just mentioned, along with others, are better is an orthogonal projection to scale of the cochlear spiral, as seen in enlarged views of the different regions. Five such views represented for a particular ear in Fig. 2. Section numbers are given by the drawings and photomicrographs of Figs. 4-8, are shown on the left. which include two positions in the lower basal and one each in This ear contains a little over two cochlear turns, and the the other three half-turns. The locations along the cochlea of length of the basilar membrane, found by stepping off the all five figures are indicated by the numbered circles of Fig. 2. distances from the basal end as shown, is 38.5 mm. The con- (a) In the basal region there is no clear distinction between centricity of the constructed spiral indicates the accuracy of external sulcus cells and Claudius cells. These tall columnar orienting the block of tissue in sectioning. cells extend as a continuous row from the edge of the basilar membrane along the shallow sulcus to the thickest portion RESULTS of the spiral ligament. In the apical region, a distinction might All the suitable specimens were thoroughly studied, and all be made: the Claudius cells may be taken as those over the enter into our conceptions of the anatomical relations. For basilar membrane and the external sulcus cells as the ones simplicity of presentation, however, we mainly picture a single turning upward along the spiral ligament. specimen, the one whose spiral is given in Fig. 2. From the basal-end upward these cells undergo a progres- sive change in size, from a maximum height in the basal General orientation region around 145 /im to about 7 /Am in the upper apical A mid-modiolar section of the cochlea is shown at low power region. At the same time the epithelial strip greatly changes its in Fig. 3, in which the cochlear spiral is cut through at four form. places. Reference to Fig. 2 at the level of Section 158 will show Kolmer described these large cells in Phocaena as showing a that this number of cuts must occur, and will show also that series of infoldings along their sides, a feature that he con- these cuts are nearly transverse, i.e., are nearly perpendicular sidered usual in mammals. No such feature is seen in our to the course of the basilar membrane. better specimens. Something similar appears in our poorer As we follow the four cochlear regions of Fig. 3 from lower- specimens, which we consider to be an artifact. left upward and to the right, we encounter in order the lower (b) Boettcher cells are found in most mammals only in the basal, lower apical, upper apical, and upper basal half-turns. basal part of the cochlea as a compact group of low-lying The same order is seen in the spiral diagram in going from cells on the outer edge of the basilar membrane, overlaid by left to right at the level of Section 158. the Claudius cells. These cells in Tursiops are few at the basal .W If I 11 N /I I I .. Imvvl.,. D .0I.. a,C C/ FIG. 2. A graphic reconstruction of the cochlear spiral of the FIG. 3. Photomicrograph of a mid-modiolar section of the right ear of a specimen of truncatus. cochlea of a specimen from truncatus. (X 7) Downloaded by guest on September 29, 2021 Proc.
Load more

Recommended publications
  • 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.
    [Show full text]
  • Vocabulario De Morfoloxía, Anatomía E Citoloxía Veterinaria
    Vocabulario de Morfoloxía, anatomía e citoloxía veterinaria (galego-español-inglés) Servizo de Normalización Lingüística Universidade de Santiago de Compostela COLECCIÓN VOCABULARIOS TEMÁTICOS N.º 4 SERVIZO DE NORMALIZACIÓN LINGÜÍSTICA Vocabulario de Morfoloxía, anatomía e citoloxía veterinaria (galego-español-inglés) 2008 UNIVERSIDADE DE SANTIAGO DE COMPOSTELA VOCABULARIO de morfoloxía, anatomía e citoloxía veterinaria : (galego-español- inglés) / coordinador Xusto A. Rodríguez Río, Servizo de Normalización Lingüística ; autores Matilde Lombardero Fernández ... [et al.]. – Santiago de Compostela : Universidade de Santiago de Compostela, Servizo de Publicacións e Intercambio Científico, 2008. – 369 p. ; 21 cm. – (Vocabularios temáticos ; 4). - D.L. C 2458-2008. – ISBN 978-84-9887-018-3 1.Medicina �������������������������������������������������������������������������veterinaria-Diccionarios�������������������������������������������������. 2.Galego (Lingua)-Glosarios, vocabularios, etc. políglotas. I.Lombardero Fernández, Matilde. II.Rodríguez Rio, Xusto A. coord. III. Universidade de Santiago de Compostela. Servizo de Normalización Lingüística, coord. IV.Universidade de Santiago de Compostela. Servizo de Publicacións e Intercambio Científico, ed. V.Serie. 591.4(038)=699=60=20 Coordinador Xusto A. Rodríguez Río (Área de Terminoloxía. Servizo de Normalización Lingüística. Universidade de Santiago de Compostela) Autoras/res Matilde Lombardero Fernández (doutora en Veterinaria e profesora do Departamento de Anatomía e Produción Animal.
    [Show full text]
  • Morphological and Functional Changes in a New Animal Model Of
    Laboratory Investigation (2013) 93, 1001–1011 & 2013 USCAP, Inc All rights reserved 0023-6837/13 Morphological and functional changes in a new animal model of Me´nie`re’s disease Naoya Egami1, Akinobu Kakigi1, Takashi Sakamoto1, Taizo Takeda2, Masamitsu Hyodo2 and Tatsuya Yamasoba1 The purpose of this study was to clarify the underlying mechanism of vertiginous attacks in Me´nie`re’s disease (MD) while obtaining insight into water homeostasis in the inner ear using a new animal model. We conducted both histopatho- logical and functional assessment of the vestibular system in the guinea-pig. In the first experiment, all animals were maintained 1 or 4 weeks after electrocauterization of the endolymphatic sac of the left ear and were given either saline or desmopressin (vasopressin type 2 receptor agonist). The temporal bones from both ears were harvested and the extent of endolymphatic hydrops was quantitatively assessed. In the second experiment, either 1 or 4 weeks after surgery, animals were assessed for balance disorders and nystagmus after the administration of saline or desmopressin. In the first experiment, the proportion of endolymphatic space in the cochlea and the saccule was significantly greater in ears that survived for 4 weeks after surgery and were given desmopressin compared with other groups. In the second experiment, all animals that underwent surgery and were given desmopressin showed spontaneous nystagmus and balance disorder, whereas all animals that had surgery but without desmopressin administration were asymptomatic. Our animal model induced severe endolymphatic hydrops in the cochlea and the saccule, and showed episodes of balance disorder along with spontaneous nystagmus.
    [Show full text]
  • CONGENITAL MALFORMATIONS of the INNER EAR Malformaciones Congénitas Del Oído Interno
    topic review CONGENITAL MALFORMATIONS OF THE INNER EAR Malformaciones congénitas del oído interno. Revisión de tema Laura Vanessa Ramírez Pedroza1 Hernán Darío Cano Riaño2 Federico Guillermo Lubinus Badillo2 Summary Key words (MeSH) There are a great variety of congenital malformations that can affect the inner ear, Ear with a diversity of physiopathologies, involved altered structures and age of symptom Ear, inner onset. Therefore, it is important to know and identify these alterations opportunely Hearing loss Vestibule, labyrinth to lower the risks of all the complications, being of great importance, among others, Cochlea the alterations in language development and social interactions. Magnetic resonance imaging Resumen Existe una gran variedad de malformaciones congénitas que pueden afectar al Palabras clave (DeCS) oído interno, con distintas fisiopatologías, diferentes estructuras alteradas y edad Oído de aparición de los síntomas. Por lo anterior, es necesario conocer e identificar Oído interno dichas alteraciones, con el fin de actuar oportunamente y reducir el riesgo de las Pérdida auditiva Vestíbulo del laberinto complicaciones, entre otras —de gran importancia— las alteraciones en el área del Cóclea lenguaje y en el ámbito social. Imagen por resonancia magnética 1. Epidemiology • Hyperbilirubinemia Ear malformations occur in 1 in 10,000 or 20,000 • Respiratory distress from meconium aspiration cases (1). One in every 1,000 children has some degree • Craniofacial alterations (3) of sensorineural hearing impairment, with an average • Mechanical ventilation for more than five days age at diagnosis of 4.9 years. The prevalence of hearing • TORCH Syndrome (4) impairment in newborns with risk factors has been determined to be 9.52% (2).
    [Show full text]
  • 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]
  • Reduced Connexin26 in the Mature Cochlea Increases Susceptibility to Noise-Induced Hearing Loss in Mice
    International Journal of Molecular Sciences Article Reduced Connexin26 in the Mature Cochlea Increases Susceptibility to Noise-Induced Hearing Loss in Mice Xing-Xing Zhou 1,†, Sen Chen 1,†, Le Xie 1, Yu-Zi Ji 1, Xia Wu 1, Wen-Wen Wang 1, Qi Yang 1, Jin-Tao Yu 1, Yu Sun 1,*, Xi Lin 2 and Wei-Jia Kong 1,3,* 1 Department of Otorhinolaryngology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Jiefang Avenue 1277, Wuhan 430022, China; [email protected] (X.-X.Z.); [email protected] (S.C.); [email protected] (L.X.); [email protected] (Y.-Z.J.); [email protected] (X.W.); [email protected] (W.-W.W.); [email protected] (Q.Y.); [email protected] (J.-T.Y.) 2 Department of Otolaryngology Head and Neck Surgery, Emory University School of Medicine, 615 Michael Street, Whitehead Bldg Rm#543, Atlanta, GA 30322, USA; [email protected] 3 Institute of Otorhinolaryngology, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China * Correspondence: [email protected]; (Y.S.); [email protected] (W.-J.K.); Tel.: +86-27-8535-1632 (Y.S.); +86-27-8535-1706 (W.-J.K.); Fax: +86-27-8577-6343 (Y.S. & W.-J.K.) † These authors contributed equally to this work. Academic Editor: Nicholas Delihas Received: 20 January 2016; Accepted: 22 February 2016; Published: 26 February 2016 Abstract: Connexin26 (Cx26, encoded by GJB2) mutations are the most common cause of non-syndromic deafness. GJB2 is thought to be involved in noise-induced hearing loss (NIHL). However, the role of Cx26 in NIHL is still obscure.
    [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]
  • Audiology 101: an Introduction to Audiology for Nonaudiologists Terry Foust, Aud, FAAA, CC-SLP/A; & Jeff Hoffman, MS, CCC-A
    NATIONALA RESOURCE CENTER GUIDE FOR FOR EARLY HEARING HEARING ASSESSMENT DETECTION & & MANAGEMENT INTERVENTION Chapter 5 Audiology 101: An Introduction to Audiology for Nonaudiologists Terry Foust, AuD, FAAA, CC-SLP/A; & Jeff Hoffman, MS, CCC-A Parents of young Introduction What is an audiologist? children who are arents of young children who are An audiologist is a specialist in hearing identified as deaf or hard identified as deaf or hard of hearing and balance who typically works in of hearing (DHH) are P(DHH) are suddenly thrust into a either a medical, private practice, or an suddenly thrust into a world of new concepts and a bewildering educational setting. The primary roles of world of new concepts array of terms. What’s a decibel or hertz? an audiologist include the identification and a bewildering array What does sensorineural mean? Is a and assessment of hearing and balance moderate hearing loss one to be concerned problems, the habilitation or rehabilitation of terms. about, since it’s only moderate? What’s of hearing and balance problems, and the a tympanogram or a cochlear implant? prevention of hearing loss. When working These are just a few of the many questions with infants and young children, the that a parent whose child has been primary focus of audiology is hearing. identified as DHH may have. In addition to parents, questions also arise from Audiologists are licensed by the state in professionals and paraprofessionals who which they practice and may be members work in the field of early hearing detection of the American Speech-Language- and intervention (EHDI) and are not Hearing Association (ASHA), American audiologists.
    [Show full text]
  • The Notch Ligand Jagged1 Is Required for the Formation, Maintenance, And
    bioRxiv preprint doi: https://doi.org/10.1101/2020.05.04.076448; this version posted May 5, 2020. The copyright holder for this preprint (which was not certified by peer review) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made available under aCC-BY-ND 4.0 International license. 1 Title: The Notch Ligand Jagged1 is Required for the Formation, Maintenance, and 2 Survival of Hensen Cells in the Mouse Cochlea. 3 4 Elena Chrysostomou1, *, Luyi Zhou2, *, Yuanzhao L. Darcy2, Kaley A. Graves2, Angelika 5 Doetzlhofer1, $, and Brandon C. Cox2,3, $ 6 7 1. The Solomon H. Snyder Department of Neuroscience and Center for Sensory 8 Biology, Johns Hopkins University School of Medicine, Baltimore, Maryland, 21205 9 2. Departments of Pharmacology and 3. Otolaryngology, Southern Illinois University 10 School of Medicine, Springfield, Illinois, 62702 11 * Denotes co-first authors, $ denotes co-corresponding authors 12 13 Corresponding authors email addresses: 14 Angelika Doetzlhofer: [email protected] 15 Brandon C. Cox: [email protected] 16 17 18 19 20 21 bioRxiv preprint doi: https://doi.org/10.1101/2020.05.04.076448; this version posted May 5, 2020. The copyright holder for this preprint (which was not certified by peer review) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made available under aCC-BY-ND 4.0 International license. 22 ABSTRACT 23 During cochlear development, the Notch ligand JAGGED 1 (JAG1) plays an important 24 role in the specification of the prosensory region, which gives rise to sound-sensing hair 25 cells and neighboring supporting cells (SCs).
    [Show full text]
  • Anatomy of the Ear ANATOMY & Glossary of Terms
    Anatomy of the Ear ANATOMY & Glossary of Terms By Vestibular Disorders Association HEARING & ANATOMY BALANCE The human inner ear contains two divisions: the hearing (auditory) The human ear contains component—the cochlea, and a balance (vestibular) component—the two components: auditory peripheral vestibular system. Peripheral in this context refers to (cochlea) & balance a system that is outside of the central nervous system (brain and (vestibular). brainstem). The peripheral vestibular system sends information to the brain and brainstem. The vestibular system in each ear consists of a complex series of passageways and chambers within the bony skull. Within these ARTICLE passageways are tubes (semicircular canals), and sacs (a utricle and saccule), filled with a fluid called endolymph. Around the outside of the tubes and sacs is a different fluid called perilymph. Both of these fluids are of precise chemical compositions, and they are different. The mechanism that regulates the amount and composition of these fluids is 04 important to the proper functioning of the inner ear. Each of the semicircular canals is located in a different spatial plane. They are located at right angles to each other and to those in the ear on the opposite side of the head. At the base of each canal is a swelling DID THIS ARTICLE (ampulla) and within each ampulla is a sensory receptor (cupula). HELP YOU? MOVEMENT AND BALANCE SUPPORT VEDA @ VESTIBULAR.ORG With head movement in the plane or angle in which a canal is positioned, the endo-lymphatic fluid within that canal, because of inertia, lags behind. When this fluid lags behind, the sensory receptor within the canal is bent.
    [Show full text]
  • Renewed Proliferation in Adult Mouse Cochlea and Regeneration of Hair Cells
    ARTICLE https://doi.org/10.1038/s41467-019-13157-7 OPEN Renewed proliferation in adult mouse cochlea and regeneration of hair cells Yilai Shu1,2,3,4,10, Wenyan Li1,2,3,4,10, Mingqian Huang1,2,10, Yi-Zhou Quan1,2,10, Deborah Scheffer1,2,5, Chunjie Tian1,2, Yong Tao1,2, Xuezhong Liu6, Konrad Hochedlinger 7,8,9, Artur A. Indzhykulian1,2, Zhengmin Wang3,4, Huawei Li3,4 & Zheng-Yi Chen 1,2* The adult mammalian inner ear lacks the capacity to divide or regenerate. Damage to inner 1234567890():,; ear generally leads to permanent hearing loss in humans. Here, we present that repro- gramming of the adult inner ear induces renewed proliferation and regeneration of inner ear cell types. Co-activation of cell cycle activator Myc and inner ear progenitor gene Notch1 induces robust proliferation of diverse adult cochlear sensory epithelial cell types. Transient MYC and NOTCH activities enable adult supporting cells to respond to transcription factor Atoh1 and efficiently transdifferentiate into hair cell-like cells. Furthermore, we uncover that mTOR pathway participates in MYC/NOTCH-mediated proliferation and regeneration. These regenerated hair cell-like cells take up the styryl dye FM1-43 and are likely to form con- nections with adult spiral ganglion neurons, supporting that Myc and Notch1 co-activation is sufficient to reprogram fully mature supporting cells to proliferate and regenerate hair cell- like cells in adult mammalian auditory organs. 1 Department of Otolaryngology-Head and Neck Surgery, Graduate Program in Speech and Hearing Bioscience and Techology and Program in Neuroscience, Harvard Medical School, Boston, MA 02115, USA.
    [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]