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Adult hearing embryonic origins.jpg

(More? Hearing | Lecture - Hearing | Child Notes - Neonatal Hearing Screening | Search Pubmed)

Hearing Links: Introduction | Inner Ear | Middle Ear | Outer Ear


The International Journal of Developmental Biology

Ear Development

The International Journal of Developmental Biology Vol. 51 Nos. 6/7 (2007) Ear Development


Introductory paper


Interview


Induction and otic placode specification


Regional patterning


Morphogenesis


Neurons and innervation


Sensory epithelia


Genetics of function & disease


Ear regeneration


Development & evolution of the ear




This issue


Purchase this issue



Cover legend The mammalian inner ear is the sensory organ responsible for balance and hearing. The developmental processes required for its formation are complicated. The cover illustration depicts representative stages of developing mouse inner ear, from a simple cyst stage in embryos to the mature pattern at birth, visualized by filling the cavity of the inner ears with paint. For further details, see article by Bok et al., 521-533.

Preface. Ear Development. Fernando Giraldez and Bernd Fritzsch Int. J. Dev. Biol. (2007) 51: 427-427 [Abstract] [FullText Open Access]

Introductory paper

The molecular biology of ear development - "Twenty years are nothing" Fernando Giraldez and Bernd Fritzsch Int. J. Dev. Biol. (2007) 51: 429-438 [Abstract] [FullText]

Interview

In pursuit of communication. An interview with Bob Ruben Fernando Giraldez and Bernd Fritzsch Int. J. Dev. Biol. (2007) 51: 439-445 [Abstract] [FullText]

Induction and otic placode specification

The preplacodal region: an ectodermal domain with multipotential progenitors that contribute to sense organs and cranial sensory ganglia Andrea Streit Int. J. Dev. Biol. (2007) 51: 447-461 [Abstract] [FullText]

The first steps towards hearing: mechanisms of otic placode induction Takahiro Ohyama, Andrew K. Groves and Kareen Martin Int. J. Dev. Biol. (2007) 51: 463-472 [Abstract] [FullText]

Expression and functions of FGF ligands during early otic development Thomas Schimmang Int. J. Dev. Biol. (2007) 51: 473-481 [Abstract] [FullText]

Regional patterning

Establishment of a proneural field in the inner ear Gina Abelló and Berta Alsina Int. J. Dev. Biol. (2007) 51: 483-493 [Abstract] [FullText]

Hindbrain signals in otic regionalization: walk on the wild side Sylvie Schneider-Maunoury and Cristina Pujades Int. J. Dev. Biol. (2007) 51: 495-506 [Abstract] [FullText]

Axial patterning in the developing vertebrate inner ear Tanya T. Whitfield and Katherine L. Hammond Int. J. Dev. Biol. (2007) 51: 507-520 [Abstract] [FullText]

Morphogenesis

Patterning and morphogenesis of the vertebrate inner ear Jinwoong Bok, Weise Chang and Doris K. Wu Int. J. Dev. Biol. (2007) 51: 521-533 [Abstract] [FullText]

Shaping the mammalian auditory sensory organ by the planar cell polarity pathway Michael Kelly and Ping Chen Int. J. Dev. Biol. (2007) 51: 535-547 [Abstract] [FullText]

Neurons and innervation

Axon guidance in the inner ear Donna M. Fekete and Andrea M. Campero Int. J. Dev. Biol. (2007) 51: 549-556 [Abstract] [FullText Open Access]

A network of growth and transcription factors controls neuronal differentation and survival in the developing ear Hortensia Sánchez-Calderón, Marta Milo, Yolanda León and Isabel Varela-Nieto Int. J. Dev. Biol. (2007) 51: 557-570 [Abstract] [FullText]

Sensory epithelia

Cellular commitment and differentiation in the organ of Corti Matthew W. Kelley Int. J. Dev. Biol. (2007) 51: 571-583 [Abstract] [FullText]

Pocket proteins and cell cycle regulation in inner ear development Sonia M.S. Rocha-Sanchez and Kirk W. Beisel Int. J. Dev. Biol. (2007) 51: 585-595 [Abstract] [FullText]

Development of the hair bundle and mechanotransduction Gowri D. Nayak, Helen S.K. Ratnayaka, Richard J. Goodyear and Guy P. Richardson Int. J. Dev. Biol. (2007) 51: 597-608 [Abstract] [FullText]

Genetics of function & disease

Mouse models to study inner ear development and hereditary hearing loss Lilach M. Friedman, Amiel A. Dror and Karen B. Avraham Int. J. Dev. Biol. (2007) 51: 609-631 [Abstract] [FullText]

Ear regeneration

Hair cell regeneration in the avian auditory epithelium Jennifer S. Stone and Douglas A. Cotanche Int. J. Dev. Biol. (2007) 51: 633-647 [Abstract] [FullText]

Non-sensory cells in the deafened organ of Corti: approaches for repair Yehoash Raphael, Young-Ho Kim, Yasunori Osumi and Masahiko Izumikawa Int. J. Dev. Biol. (2007) 51: 649-654 [Abstract] [FullText]

Stem cells for the replacement of inner ear neurons and hair cells Rodrigo Martinez-Monedero and Albert S.B. Edge Int. J. Dev. Biol. (2007) 51: 655-661 [Abstract] [FullText]

Development & evolution of the ear

Molecular evolution of the vertebrate mechanosensory cell and ear Bernd Fritzsch, Kirk W. Beisel, Sarah Pauley and Garrett Soukup Int. J. Dev. Biol. (2007) 51: 663-678 [Abstract] [FullText]

Development of Johnston's organ in Drosophila Daniel F. Eberl and Grace Boekhoff-Falk Int. J. Dev. Biol. (2007) 51: 679-687 [Abstract] [FullText]

The International Journal of Developmental Biology

ISSN 1696-3547 (online) and 0214-6282 (print)


http://www.ncbi.nlm.nih.gov/pubmed/19750520

Specification of cell fate in the mammalian cochlea.

"Mammalian auditory sensation is mediated by the organ of Corti, a specialized sensory epithelium found in the cochlea of the inner ear. Proper auditory function requires that the many different cell types found in the sensory epithelium be precisely ordered within an exquisitely patterned cellular mosaic. The development of this mosaic depends on a series of cell fate decisions that transform the initially nearly uniform cochlear epithelium into the complex structure of the mature organ of Corti. The prosensory domain, which contains the progenitors of both the mechanosensory hair cells and their associated supporting cells, first becomes distinct from both the neural and the nonsensory domains. Further cell fate decisions subdivide prosensory cells into populations of inner and outer hair cells, and several different types of supporting cells. A number of different signaling pathways and transcription factors are known to be necessary for these developmental processes; in this review, we will summarize these results with an emphasis on recent findings."


File:Hearingcartoon.jpg We use the sense of balance and hearing to position ourselves in space, sense our surrounding environment, and to communicate. Portions of the ear appear very early in development as specialized region (otic placode) on the embryo surface that sinks into the mesenchyme to form a vesicle (otic vesicle = otocyst) that form the inner ear.

Further detailed notes covering specific topics are on linked pages.

This region connects centrally to the nervous system and peripherally through specialized bones to the external ear (auricle). This organisation develops different sources forming the 3 ear parts: inner ear (otic placode, otocyst), middle ear (1st pharyngeal pouch and 1st and 2nd arch mesenchyme), and outer ear (1st pharyngeal cleft and 6 surface hillocks).

This complex origin, organisation, and timecourse means that abnormal development of any one system can impact upon the development of hearing.

File:A3.gifStage 13 Head showing the paired otocysts that form the inner ear
File:Hb5.gifStage 22 Human head cross-section showing inner, middle and outer ear structures.
Look first at the early and late embryonic stage images of structures associated with this system.

Page Links: [#Intro Introduction] | [#recent Some Recent Findings] | [#timing Development Timing] | [#Reading Reading] | [#Computer Computer Activities] | [#Objectives Objectives] | [#timing Development Timing] | [#Inner Ear Inner Ear] | [#Middle Ear Middle Ear] | [#Outer Ear Outer Ear] | [#overview Development Overview] | [#stage13 stage 13/14 embryo] | [#stage22 stage 22 embryo] | [#stage22select stage 22 embryo highpower] | [#LectureSlides Science Lecture (2004) Slides] | [#Congenital_Deafness Congenital Deafness] | [#Conductive Conductive Hearing Loss] | [#References References] | [#Glossary Glossary] | [#Glossary Terms]

Related Pages: [ear6.htm Inner Ear] | [ear7.htm Middle Ear] | [ear8.htm Outer Ear] | [ear9.htm Central Pathway] | [ear2.htm Abnormalities] | [ear3.htm Stage 13/14] | [ear4.htm Stage 22] | [ear5.htm Stage 22 Selected] | [ear11.htm Molecular] | [week4_3.htm.htm Week 4 Placode Development] || [head.htm Head Notes] | [face.htm Face Notes] | [neuron.htm Neural Notes]

Some Recent Findings

File:Earlabyrinthsm.jpg[images/senses/earlabyrinth.jpg Inner ear labyrinth]

Werner LA. Issues in human auditory development. J Commun Disord. 2007 Mar 13;

Sage C, Huang M, Vollrath MA, Brown MC, Hinds PW, Corey DP, Vetter DE, Chen ZY. Essential role of retinoblastoma protein in mammalian hair cell development and hearing. Proc Natl Acad Sci U S A. 2006 Apr 28;

"The retinoblastoma protein pRb is required for cell-cycle exit of embryonic mammalian hair cells but not for their early differentiation. However, its role in postnatal hair cells is unknown. ...This study reveals essential yet distinct roles of pRb in cochlear and vestibular hair cell maturation, function, and survival and suggests that transient block of pRb function in mature hair cells may lead to propagation of functional hair cells."

Mantela J, Jiang Z, Ylikoski J, Fritzsch B, Zacksenhaus E, Pirvola U. The retinoblastoma gene pathway regulates the postmitotic state of hair cells of the mouse inner ear. Development. 2005 May;132(10):2377-88. Epub 2005 Apr 20.

Rowe TM, Rizzi M, Hirose K, Peters GA, Sen GC. A role of the double-stranded RNA-binding protein PACT in mouse ear development and hearing. Proc Natl Acad Sci U S A. 2006 Mar 29;

".. Pact(-/-) mouse were reduced size and severe microtia. As a result of the congenital abnormality of both outer and middle ears, these mice were hearing impaired. Our study demonstrated an essential role of PACT in mammalian ear development and produced the first animal model for studying human microtia."

For more articles see [#References References].

Reading

  • Human Embryology (2nd ed.) Larson Ch12: p375-409
  • The Developing Human: Clinically Oriented Embryology (6th ed.) Moore and Persaud Ch19: p491-511
  • Essentials of Human Embryology Larson Ch12: p252-272
  • Before We Are Born (5th ed.) Moore and Persaud Ch20: p460-479
  • Online References: [#OnlineTextbooks OnlineTextbooks] | [#References References] | [#SearchPubMed Search PubMed]

Objectives

  • Understanding of structures and functions of the auditory pathway
  • Understanding of inner, middle and external ear origins
  • Understanding of timecourse of auditory development
  • Understanding of abnormalities of auditory development
  • Brief understanding of central auditory pathway and molecular development

Computer Activities

UNSW Embryology: [ear3.htm Stage 13/14] | [ear4.htm Stage 22] | [ear4.htm Stage 22] | [ear5.htm Stage 22 Selected] | [ear2.htm Hearing Abnormalities] | Following pages under development: [ear6.htm Inner Ear] | [ear7.htm Middle Ear] | [ear8.htm Outer Ear] | [ear11.htm Molecular] | [../wwwhuman/System/HumSysN.htm Human Systems] | [../wwwhuman/LowSet/HeadSet.htm#A6-B3 Stage 22 Head Set] | [../wwwpig/lowset/HeadSet.htm#A6-B3 Stage 13/14 Head Set]

Science Lecture: [../Science/ANAT2341lecture17.htm 2008 ANAT2341 Lecture 17 Hearing] These documents are also linked from the [../class.htm Class Notes] page.

PDF 2004 Slides: [../Sections/anat2310/2004/ANAT2310L5Ears1.pdf Lecture 05 Hearing, 1 Slide / Page for Viewing] | [../Sections/anat2310/2004/ANAT2310L5Ears4.pdf Lecture 05 Hearing, 4 Slides / Page for Printing]

Embryo Images Unit: Embryo Images Online | Ear Development | Inner Ear | Middle Ear | External Ear

Movies: [../Movies/senses.htm.htm Senses Movies]

Development Timing

Week 3 - otic placode, otic vesicle

Week 5 - cochlear part of otic vesicle elongates (humans 2.5 turns)

Week 9 - Mesenchyme surrounding membranous labryinth (otic capsule) chondrifies

Week 12-16 - Capsule adjacent to membranous labryinth undegoes vacuolization to form a cavity (perilymphatic space) around membranous labrynth and fills with perilymph

Week 16-24 - Centres of ossification appear in remaining cartilage of otic capsule form petrous portion of temporal bone. Continues to ossify to form mastoid process of temporal bone.

3rd Trimester - Vibration acoustically of maternal abdominal wall induces startle response in fetus.

(These are Human embryonic timings, not clinical which is based on last menstral period +2 weeks)

3 Sources:

Inner ear - epidermal otic placode at level of hindbrain.

Middle ear - cavity: 1st pharyngeal pouch, ossicles: mesenchyme 1st and 2nd pharyngeal arches.

Outer ear - external auditory meatus: 1st pharyngeal cleft, auricle: 6 hillocks 1st and 2nd pharyngeal arches.

Inner Ear

File:Earlabyrinthsm.jpg There is a detailed notes page covering [ear6.htm Inner Ear Development].

The inner ear is derived from a pair of surface sensory placodes (otic placodes) in the head region. These placodes fold inwards forming a depression, then pinch off entirely from the surface forming a fluid-filled sac or vesicle (otic vesicle, otocyst). The vesicle sinks into the head mesenchyme some of which closely surrounds the otocyst forming the otic capsule. The otocyst finally lies close to the early developing hindbrain (rhombencephalon) and the developing vestibulo-cochlear-facial ganglion complex.

External Link: Embryo Images Unit - Inner Ear

Middle Ear

File:Ear ossicles sm.jpg There is a detailed notes page covering [ear7.htm Middle Ear Development].

The middle ear ossicles (bones) are derived from 1st and 2nd arch mesenchyme. The space in which these bones sit is derived from the 1st pharyngeal pouch.

External Link: Embryo Images Unit - Middle Ear

Outer Ear

File:External ear sm.jpg There is a detailed notes page covering [ear8.htm Outer Ear Development].

The external ear is derived from 6 surface hillocks, 3 on each of pharyngeal arch 1 and 2. The external auditory meatus is derived from the 1st pharyngeal cleft. The newborn external ear structure and position is an easily accessible diagnostic tool for potential abnormalities or further clinical screening.

External Link: Embryo Images Unit - External Ear

Stage 13/14 Embryo

File:A2.gif File:A3.gif File:A4.gif File:A5.gif
[../wwwpig/piga/A2L.htm A2]: Otocyst (R). Apex of otocyst (primordium of L endolymphatic sac). [../wwwpig/piga/A3L.htm A3]: Otocyst; surrounding mesenchyme = otic capsule. Note proximity of otocyst to wall of rhombencephalon. Superior glossopharyngeal ganglion. Vestibulo-cochlear-facial ganglion complex (R). [../wwwpig/piga/A4L.htm A4]: Indentation in rostral margin of otocyst = primordium of utriculosaccular canal. Note alignment of superior cardinal vein (LS) in relation to the nerve trunks (XS). Trigeminal ganglion (not in image excerpt). Note variation in height of cells of L otocyst wall. [../wwwpig/piga/A5L.htm A5]: Facial ganglion (R). "Floor" of L otocyst. Note on R, the former position of the otocyst in relation to the 2nd pharyngeal arch.

Stage 22 Embryo

File:Hb3ear.gif [../wwwhuman/lowpower/HumB/B3L.htm B3:] Rhombic lip (developing cerebellum). IVth ventricle. Trigeminal ganglion. Adenohypophysis. Sphenoid cartilage.
File:Hb4ear.gif [../wwwhuman/lowpower/HumB/B4L.htm B4]: Cochlear duct and temporal cartilage. Semicircular duct (ampulla on L). precartilage of auricle (pinna). malleus (medial, L). Incus (lateral, L).
File:Hb5.gif [../wwwhuman/lowpower/HumB/B5L.htm B5]: Extemal auditory meatus. Auricle. Incus (dorsal). Malleus (ventral). Tubotympanic recess (auditory rube). Tensor tympani m. (L). Utricle. Semicircular ducts. Intemal auditory meatus (R), containing vestibular and spiral ganglia. Endolymphatic sac (L). Note proximity of sac to choroid plexus of 4th ventricle.
File:Hb6.gif [../wwwhuman/lowpower/HumB/B6L.htm B6]: External auditory meatus. Primordium of tympanic membrane (L). Manubrium of malleus(L). Basal turn of cochlea duct (L). Endolymphatic sac (R). Common crus (R). Junction of utricle and saccule (R). Meckel's cartilage. Stapes (R). Auditory tube.

Stage 22 Embryo (selected)

File:HumHPB3L.GIFRegions of stage 22 embryo head (mouth at top) in selected images of inner ear below


Developmental Overview

Development of Hearing - 3 divisions of ear

  • outer
    • external auditory meatus (ear canal)
    • functions to collect sound and gude it to the tympanic membrane
  • middle
    • tympanic cavity
    • functions to convert sound pressure waves into mechanical waves of typanic membrane
    • ossicles reduce amplitude but increase force to drive fluid-filled inner ear
    • eustacian tube allows equalization of pressure (into oral cavity)
  • inner
    • duct system
    • functions to convert hair displacement into neural signals
    • cochlear (sound)
    • semicircular canals (balance)
    • vestibulocochlear nerve
    • Organ of Corti
    • Hair Cells
  • Pinna- Auricle
  • develops from six aural hillocks
  • 3 on first arch
  • 3 on second arch
  • originally on neck, moves cranially during mandible development
  • Outer- external auditory meatus
  • derived from first pharyngeal cleft
  • ectodermal diverticulum
  • week 5
  • extends inwards to pharynx
  • until week 18 has ectodermal plug
  • plug forms stratified squamous epithelia of canal and outer eardrum
  • Outer Ear Genes
    • controlled by genes that regulate arch 1 and 2 development
    • related to hindbrain segmentation (rhombomere 4)
  • Mouse
    • Hox a1/Hoxb1, goosecoid, Endothelin1, dHAND
  • Middle- tympanic cavity
  • derived from first pharyngeal pouch
  • extends as tubotympanic recess
  • during week 5 recess contacts outer ear canal
  • mesoderm between 2 canals forms tympanic membrane
  • expands to form tympanic recess
  • stalk of recess forms eustacian tube
  • pharyngotympanic tube
  • Middle- Ossicles
  • develop from first and second pharyngeal arches
  • tympanic cavity enlarges to incorporate
  • coats with epithelia
  • first arch mesoderm
  • tensor tympani muscle
  • malleus and incus
  • second arch mesoderm
  • stapedius muscle and stapes
  • Middle Ear Genes
  • gooscoid, RARs, Prx1, Otx2, Hoxa1, Hoxb1, endothelian related molecules
  • Inner- otocyst
  • week 3 otic placode forms on surface ectoderm
  • otic placode sinks into mesoderm
  • forms otocyst (otic vesicle)
  • Otic Vesicle to Labyrinth 1
  • Pig stage 13/14 Otocyst
  • Otocyst
  • branches form and generate endolymphatic duct and sac
  • forms vestibular and cochlear sac
  • Vestibular sac
  • generates 3 expansions
  • form semicircular ducts
  • remainder forms utricle
  • epithelia lining generates
  • hair cells
  • ampullary cristae
  • utricular macula
  • Otic Vesicle to Labyrinth
  • Human Stage 22
  • Vestibular- Otoconia
  • Otoconin- inner ear biominerals
  • Cochlear sac
  • generates coiled cochlear duct
  • humans 2 1/2 turns
  • remainder forms saccule
  • epithelia lining generates
  • hair cells
  • structures of organ of corti
  • saccular macula
  • Human Stage 22- cochlear
  • Human Stage 22- cochlear
  • Bony Labyrinth
  • formed from chrondified mesoderm
  • Periotic Capsule
  • mesenchyme within capsule degenerates to form space filled with perilymph
  • Vestibulocochlear Nerve
  • forms beside otocyst
  • from wall of otocyst and neural crest cells
  • bipolar neurons
  • vestibular neurons
    • outer end of internal acoustic meatus
    • innervate hair cells in membranous labyrinth
    • axons project to brain stem and synapse in vestibular nucleus
  • cochlear neurons
    • cell bodies lie in modiolus
    • central pillar of cochlear
    • innervate hair cells of spiral organ
    • axons project to cochlear nucleus
  • Inner Ear Genes
  • hindbrain segmentation occurs at same time placode arises
  • otocyst adjacent to rhombomere 5
  • may influence development
  • Hoxa1, kreisler, Fgf3
  • genes regulating neural crest cells (neural genes)
  • Pax2 Ko affects cochlear and spiral ganglion, but not vestibular apparatus
  • nerogenin 1 affects both ganglia
  • Semicircular canal
  • Otx1- cochlear and vestibular normal
  • Hmx3, Prx1, Prx2
  • Sensory Organs
  • thyroid hormone receptor beta
  • Zebrafish-mindbomb mutant
    • excess hair cells but not supporting cells
      • Notch-Delta signaling
  • Gene Expression-inner ear
  • Brn-3c and Hair cell development
  • Supporting Cells- p27kip
  • Thyroid Hormone
  • Ganglion neurons require growth factors
  • vestibular neurons- BDNF, NT3
    • survival not development

Congenital Deafness

Conductive - disease of outer and middle ear

Sensorineural - cochlear or central auditory pathway

  • Congenital malformations Statistics
  • Congenital sensorineural hereditary or acquired (see [#References recent reviews])
  • Hereditary
  • recessive- severe
  • dominant- mild
  • can be associated with abnormal pigmentation (hair and irises)
  • Acquired
  • rubella (German measles)
  • maternal infection during 2nd month of pregnancy
  • vaccination of young girls
  • streptomycin
  • antibiotic
  • thalidomide
  • Conductive Hearing Loss
  • produced by otitis media with effusion, is widespread in young children.
  • temporary blockage of outer or middle ear
  • See also: [#Conductive recent Ref] and [senseslink.htm#Hearing%20Links Senses WWW Link]

(More? [ear2.htm Hearing Abnormalities])

Conductive Hearing Loss

  • Conductive Hearing Loss Produces a Reversible Binaural Hearing Impairment David R. Moore, Jemma E. Hine, Ze Dong Jiang, Hiroaki Matsuda, Carl H. Parsons, and Andrew J. King J. Neurosci. 1999;19 8704-8711
    • http://www.jneurosci.org/cgi/content/abstract/19/19/8704
    • tested ferrets by lon-term plugging of ear canal
    • Repeated testing during the 22 months after unplugging revealed a gradual return to normal levels of unmasking.
    • Results show that a unilateral conductive hearing loss, in either infancy or adulthood, impairs binaural hearing both during and after the hearing loss.
    • Show scant evidence for adaptation to the plug and demonstrate a recovery from the impairment that occurs over a period of several months after restoration of normal peripheral function.

(More? [ear2.htm Hearing Abnormalities])

References

Many of the links below are to external resources and require an internet connection.

Links: [#Earlier Earlier References] | [#Journals Journals] | [#OnlineTextbooks Online Textbooks] | [#SearchTextbooks Search Textbooks] | [#PubMed PubMed] | [#SearchPubMed Search PubMed] | [#Books Books] | [#Glossary Glossary]

1999 and Earlier References: [../Refer/neuron/select.htm#Neuralation Neuralation] | [../Refer/neuron/select.htm#Notch Notch Articles/Reviews] | [../Refer/neuron/select.htm#SHH Sonic Hedgehog Articles/Reviews] | [../Refer/neuron/select.htm#Dorsal Dorsal] | [../Refer/neuron/select.htm#Clinical Clinical] | [../Refer/neuron/select.htm#Folate Folate] |

Journals

Developmental Brain Research Content Listing

Neural Development Welcome to Neural Development | Pubmed Central Volume 1 2006 | Pubmed Central Volume 2 2007 |

International Journal for Developmental Neuroscience Official Journal of the International Society for Developmental Neuroscience |

Developmental Neuroscience Journal Homepage | Hippocampal Development | Vol. 29, No. 3, 2007 |

Neuroscience Official journal of The International Brain Research Organisation (IBRO)

Neuron Neuroscience journal published by Cell press

Online Textbooks

Developmental Biology (6th ed) Gilbert, Scott F. Sunderland (MA): Sinauer Associates, Inc.; c2000. Evolution of the mammalian middle ear bones from the reptilian jaw | Chick embryo rhombomere neural crest cells | Some derivatives of the pharyngeal arches | Formation of the Neural Tube | Differentiation of the Neural Tube | Tissue Architecture of the Central Nervous System | Neuronal Types | Snapshot Summary: Central Nervous System and Epidermis

Neuroscience Purves, Dale; Augustine, George J.; Fitzpatrick, David; Katz, Lawrence C.; LaMantia, Anthony-Samuel; McNamara, James O.; Williams, S. Mark. Sunderland (MA): Sinauer Associates, Inc. ; c2001 The Auditory System | The Inner Ear | The Middle Ear | The External Ear | Early Brain Development | Construction of Neural Circuits | Modification of Brain Circuits as a Result of Experience

Molecular Biology of the Cell (4th Edn) Alberts, Bruce; Johnson, Alexander; Lewis, Julian; Raff, Martin; Roberts, Keith; Walter, Peter. New York: Garland Publishing; 2002. Neural Development | The three phases of neural development

Clinical Methods 63. Cranial Nerves IX and X: The Glossopharyngeal and Vagus Nerves | The Tongue | 126. The Ear and Auditory System | An Overview of the Head and Neck - Ears and Hearing | Audiometry

Health Services/Technology Assessment Text (HSTAT) Bethesda (MD): National Library of Medicine (US), 2003 Oct. Developmental Disorders Associated with Failure to Thrive

Eurekah Bioscience CollectionCranial Neural Crest and Development of the Head Skeleton

Search NLM Online Textbooks- "neural development" : Developmental Biology | The Cell- A molecular Approach | Molecular Biology of the Cell | Endocrinology

Reviews

Werner LA. Issues in human auditory development. J Commun Disord. 2007 Mar 13;

Barald KF, Kelley MW. From placode to polarization: new tunes in inner ear development. Development. 2004 Sep;131(17):4119-30. Review.

Morsli H, Choo D, Ryan A, Johnson R, Wu DK. Development of the mouse inner ear and origin of its sensory organs. J Neurosci. 1998 May 1;18(9):3327-35. J Neuroscience Link

Articles

Villa-Cuesta E, Modolell J. Mutual repression between msh and Iro-C is an essential component of the boundary between body wall and wing in Drosophila. Development. 2005 Aug 10

Goto M, Piper Hanley K, Marcos J, Wood PJ, Wright S, Postle AD, Cameron IT, Mason JI, Wilson DI, Hanley NA. In humans, early cortisol biosynthesis provides a mechanism to safeguard female sexual development. J Clin Invest. 2006 Apr;116(4):953-60.

Jones JM, Montcouquiol M, Dabdoub A, Woods C, Kelley MW. Inhibitors of differentiation and DNA binding (Ids) regulate Math1 and hair cell formation during the development of the organ of Corti. J Neurosci. 2006 Jan 11;26(2):550-8.

"Basic helix-loop-helix (bHLH) transcription factor Math1 (Mouse homolog of ATH1, also called Atoh1) is both necessary and sufficient for hair cell development in the mammalian cochlea. The bHLH-related inhibitors of differentiation and DNA binding (Id) proteins negatively regulate many bHLH transcription factors including Math1. Progenitor cells expressing Ids during the time of hair cell differentiation were inhibited from developing as hair cells. Role for Ids in the regulation of expression of Math1 and hair cell differentiation in the developing cochlea." (text edited from abstract) (More? OMIM ATONAL)

Rodriguez-Vazquez JF. Development of the stapes and associated structures in human embryos. J Anat. 2005 Aug;207(2):165-73.

"The stapedial anlage is a unique formation with two distinct parts: the superior part that will comprise the base and the inferior part that will be crossed by the stapedial artery during embryonic development and will constitute the limbs and the head of the stapes. According to the results, the otic capsule is not involved in formation of the base of the stapes."

Kiernan AE, Pelling AL, Leung KK, Tang AS, Bell DM, Tease C, Lovell-Badge R, Steel KP, Cheah KS. Sox2 is required for sensory organ development in the mammalian inner ear. Nature. 2005 Apr 21;434(7036):1031-5.

"Sensory hair cells and their associated non-sensory supporting cells in the inner ear are fundamental for hearing and balance. They arise from a common progenitor, but little is known about the molecular events specifying this cell lineage."

Molecular Normal Development

Jones JM, Montcouquiol M, Dabdoub A, Woods C, Kelley MW. [See Related Articles ] Inhibitors of differentiation and DNA binding (Ids) regulate Math1 and hair cell formation during the development of the organ of Corti. J Neurosci. 2006 Jan 11;26(2):550-8.

Kawamoto K, Ishimoto S, Minoda R, Brough DE, Raphael Y. [See Related Articles ] Math1 gene transfer generates new cochlear hair cells in mature guinea pigs in vivo. J Neurosci. 2003 Jun 1;23(11):4395-400.

Zine A, de Ribaupierre F. [See Related Articles ] Notch/Notch ligands and Math1 expression patterns in the organ of Corti of wild-type and Hes1 and Hes5 mutant mice. Hear Res. 2002 Aug;170(1-2):22-31.

List of [../Refer/senses/ear_rev.htm Ear Development Reviews (1998)]

Reviews Abnormal Development (1998)

 Webster WS. [See Related Articles ] Teratogen update: congenital rubella. Teratology. 1998 Jul;58(1):13-23. Review.

Yates JA, et al. [See Related Articles] Isolated congenital internal auditory canal atresia with normal facial nerve function. Int J Pediatr Otorhinolaryngol. 1997 Jul 18;41(1):1-8. Review.

Lambert PR, et al. [See Related Articles] Congenital malformations of the external auditory canal. Otolaryngol Clin North Am. 1996 Oct;29(5):741-60. Review.

Lin AE, et al.  [See Related Articles] Further delineation of the branchio-oculo-facial syndrome. Am J Med Genet. 1995 Mar 13;56(1):42-59. Review.

Strasnick B, et al  [See Related Articles] Teratogenic hearing loss. J Am Acad Audiol. 1995 Jan;6(1):28-38. Review.

Kossowska E, et al. [See Related Articles] Prenatal and neonatal prophylaxis in otorhinolaryngology. Int J Pediatr Otorhinolaryngol. 1980 Jun;2(2):85-98. Review.

Gottlieb G. [See Related Articles] Conceptions of prenatal development: behavioral embryology. Psychol Rev. 1976 May;83(3):215-34. Review.

Holme RH, Steel KP Genes involved in deafness. Curr Opin Genet Dev 1999 Jun;9(3):309-314

"Remarkable progress has been made over the past few years in the field of hereditary deafness. To date, mutations in at least 35 genes are known to cause hearing loss. We are now beginning to understand the function of many of these genes, which affect diverse aspects of ear development and function.

Books

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Molecular and Cellular Approaches to Neural Development

The Embryonic Human Brain: An Atlas Of Developmental Stages, 3rd Edition

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Terms

altricial animal - Term used to describe an animal born in a helpless state, with incomplete development of sensory systems at birth. For example rats and mice are born with incomplete development of visual and auditory systems.

ampulla - Term used to describe an anatomical dilation of a tube or canal lumen. Anatomical description of the opening end of the uterine tube lying above the ovary and the enlarged initial segmeny of the semicircular canals of the inner ear vestibular system. (More? [ear6.htm Inner Ear] | [genitalXXuterus.htm Genital System - Female Uterus])

aneurism - (Greek, aneurysma = a widening, aneurysm) A term used to describe an abnormal widening of a vessel or anatomical tubal structure.

aquaeductus vestibuli - see vestibular aqueduct

auditory neuropathy - (AN) abnormality of transmission of sound information to the brain.

auditory tube - (eustachian tube) between the middle ear and oral cavity, has a bony (tympanic 1/3) and cartilaginous (pharyngeal 2/3) portion. The main role is equalization of pressure and fluid drainage in the middle ear.

auricular hillock - see hillock

atresia - narrowing, usually of an anatomical tube or cavity.

autophagocytosis - (Greek, auto = self, phagy = eating, also called autophagy) a cell death mechanism that uses the cell's own lysosomes to self digest.

border cells - columnar cells within the organ of Corti on the medial portion of the basilar membrane.

canalis reuniens - (ductus reuniens, canaliculus reuniens, canalis reuniens, Hensen's canal, Hensen's duct, uniting canal, canalis reuniens of Hensen) short narrow canal connecting the cochlea duct to the saccule. (Victor Hensen, 1835-1924)

cerumen - (ear wax) produced by glands in the skin of the outer portion of the ear canal.

chondrified - the developmental differentiation of cartilage from mesenchye, an embryonic connective tissue.

cristae ampullaris - located in the ampulla of the membranous semicircular canals a region with both supporting and hair cells. The hair cell cilia are embedded in the gelatinous cupula.

claudius cells - (cells of Claudius) columnar cells with microvilli overlying the basilar membrane and extend from Hensen's cells to the spiral prominence. Barrier cells that lie external to the organ of corti in endolymph.

cochlear sac - embryonic structure, which will form the coiled cochlear duct and contribute to the saccule.

cochlear aqueduct - a bony channel containing the fibrous periotic duct. It connects the basal turn of the cochlea perilymphatic space with the subarachnoid space of the posterior cranial cavity.

cochlin - major constituent of the inner ear extracellular matrix.

collagen type II - major constituent of the inner ear extracellular matrix.

conductive loss - term used to describe one of the two major classes of hearing loss involving external and middle ear abnormalities (other form is Sensorineural loss).

connexins - channel proteins of the gap junctions that allow rapid communication between adjacent cells. The two connexins Cx26 and Cx30 are the major proteins of cochlear gap junctions.

connexin 26 - A strikingly high proportion (50%) of congenital bilateral nonsyndromic sensorineural deafness cases have been linked to mutations in the GJB2 coding for the connexin26

cupular deposits - basophilic material on the cupulae of the semicircular ducts, an postnatal ageing phenomenon seen in some vestibular labyrinth.

clinical weeks - taken from last menstrual period (LMP) and therefore approximately two weeks before fertilization occurs.

Deiters' cells

discoidin domain receptor 1 - (DDR1) a tyrosine kinase receptor activated by native collagen, expressed in the basement membrane and with fibrillar collagens. Found in basal cells of the stria vascularis, type III fibrocytes, and cells lining the basilar membrane of the organ of Corti. {Meyer zum Gottesberge, 2008 #1877}

ductus utriculosaccularis -

endochondral ossification - the process of bone formation from a pre-existing cartilage template.

endoderm -

endolymphatic fluid -

endolymphatic sac - inner ear structure that has anatomically both an intraosseous and extraosseous component. Th e sac has functions regulating endolymph that are both secretory and absorptive. Also the site of endolymphatic sac tumors either sporadical occurring or associated with the autosomal-dominant von Hippel-Lindau (VHL) disease, due to a germ line mutation.

embryological weeks - taken from the time of fertilization which typically occurs around the middle (day 14), or just after, of the typical 28 day menstrual cycle.

Emx2 - homeobox gene affecting middle ear and inner ear development.

eustachian tube - (auditory tube) A cavity linking the pharynx to the middle ear, which develops from the first pharyngeal pouch. Named after Bartolomeo Eustachi (1500 - 1574) an Italian anatomist.

external auditory meatus - (ear canal) develops from the first pharyngeal cleft.

ear wax - see cerumen.

epithelia -

espins - calcium-resistant actin-bundling proteins enriched in hair cell stereocilia and sensory cell microvilli and spiral ganglion neurons (SGNs)

eustachian tube - (auditory tube) between the middle ear and oral cavity, equalization of pressure in the middle ear.

external auditory canal -

fenestra ovalis - (oval window) separates the tympanic cavity from the vestibule of the osseous labyrinth.

fenestra rotunda - (round window) separates the tympanic cavity from the scala tympani of the cochlea.

fetus - (foetus) term used to describe human development after the 8th week (10th clinical week, LPM) and covers the developmental periods of second and third trimester.

fibroblast growth factor 1 - (Fgf-1) a growth factor released from cochlea sensory epithelium which stimulates spiral ganglion neurite branching.

fibroblast growth factor 8 - (Fgf-8) a growth factor released by inner hair cells which regulates pillar cell number, position and rate of development.

fibroblast growth factor receptor 3 - (Fgfr-3) a tyrosine kinase receptor with a role in the commitment, differentiation and position of pillar cells in the organ of corti

fundamental frequency - (natural frequency) the lowest frequency in a harmonic series, for the female voice this is about 225 Hz.

helicotrema - term used to describe the cochlear apex.

Hes - (hairy and enhancer of split) family of factors, which has been shown to be a general negative regulator of neurogenesis {Zheng, 2000 #1936}.

hillock - a small hill, used to describe the six surface elevations on pharyngeal arch one and two.

Hindbrain - Invaginate -

Incus - (anvil) auditory ossicle

inner phalangeal cells

inner pillar cells - organ of Corti cells arranged in rows and form a boundary between the single row of inner hair cells and three rows of outer hair cells. These cells have surface-associated microtubule bundles.

inner sulcus - area of the cochlear duct

interdental region -

internal auditory meatus - (internal acoustic meatus, IAM) Anatomical canal in which CN VII and CN VIII ganglia reside and pass through to the brainstem. This bony canal lies between the posterior surface of the petrous pyramid and the bony labyrinth within the dense petrous bone. Also associated clinically with the site where acoustic neuromas may occur.

Kolliker's organ - (Kollicker's organ, greater epithelial ridge) Developing cochlear structure consisting of columnar-shaped supporting cells filling the inner sulcus and lying directly under the tectorial membrane. This transient organ regresses and generates the space of the inner sulcus. Rudolph Albert von Kolliker (1817-1905)??

lateral semicircular duct - Limbus -

LMP - acronym for last menstrual period, used to clinically measure gestation.

malleus - (hammer) auditory ossicle

mastoid process - of temporal bone

Math1 - homolog of the Drosophila proneural gene atonal, necessary and sufficient for the production of hair cells in the mouse inner ear. {Chen, 2002 #1932}Negatively regulated by Hes1 and Hes5

meatal plug - temporary blockage of the external auditory meatus which forms at the end of the embryonic period and remains present until the seventh month.

meatus - anatomical opening, cavity or space (external acoustic meatus,internal auditory meatus)

Meckel's cartilage - first pharyngeal ach cartilage, located within the mandibular prominence. This cartilage first appears at stage 16, stage 20 the beginning of membranous ossification. Named after Johann Friedrich Meckel, (1781 - 1833) a German anatomist. (http://www.whonamedit.com/doctor.cfm/1840.html)

membranous labyrinth - Mesenchyme - Mesoderm - Microtia - Modiolus -

mucopolysaccharidosis - (MPS IIIB, Sanfilippo Syndrome type B) abnormality caused by a deficiency in the lysosomal enzyme N-acetyl-glucosaminidase (Naglu). Children with MPS IIIB develop abnormal hearing, and mental functioning culminating in early death.

netrin-1 - secreted growth factor, expressed in the organ of Corti and spiral ganglion cells, role in process outgrowth.

neural tube -

olivocochlear - brainstem cholinergic and GABAergic efferent system that innervates sensory cells and sensory neurons of the inner ear.

organ of Corti - organ of Corti protein II - (OCP-II) cytosolic protein or transcription factor?

otolithic membrane - extracellular matrix that cover the sensory epithelia of the inner ear.

ossicle - (small bone) the individual bone of the three middle ear bones (auditory ossicles), which reduce vibrational amplitude but increase force to drive fluid-filled inner ear.

ossify -

otic capsule -

otic cup

otic placode -

otic vesicle -

otoconin - inner ear biominerals required for vestibular apparatus function.

otogelin - (Otog) an inner ear specific glycoprotein expressed in cochlea cells at different developmental times.

otolithic membrane - a membrane within the utricle and saccule containing embedded hair cell cilia and small crystalline bodies of calcium carbonate (otoliths). Functions to detect head motion.

otoliths - small crystalline bodies of calcium carbonate found within the otolitic membrane of the utricle and saccule.

ototoxic - compound or drug causing temporary or permanent hearing loss.

outer hair cells - (OHCs) three rows of hair cells that function to increase basilar membrane motion through a local mechanical feedback process within the cochlea, the "cochlear amplifier".

outer pillar cells - arranged in rows and form a boundary between the single row of inner hair cells and three rows of outer hair cells.

paratubal musculature - muscles lying beside the auditory (Eustachian) tube. The tensor veli, palatini (TVP) and tensor tympani muscles.

perilymph - perilymphatic space - Periotic Capsule - petrous portion - of temporal bone

pejvakin gene - in humans, two missense mutations in this gene cause nonsyndromic recessive deafness (DFNB59) by affecting the function of auditory neurons.

pharyngeal archpharyngeal pouchpharyngeal membranePharynx

pillar cells - (PC) form an inner and outer row of support cells that form a boundary between inner and outer hair cells.

Placode

preyer reflex - ear flick in mouse in response to sound.

presbyacusis

prestin - a motor protein structurally similar to the anion transporter family expressed in cochlear outer hair cells.

preauricular tag - skin tags located in front of the external ear opening, are common in neonates and in most cases are normal, though in some cases are indicative of other associated abnormalities.

primordium-

protocadherin 15 - (Pcdh15) required for initial formation of stereocilia bundles and changes in the actin meshwork within hair cells. The Ames waltzer (av) mouse mutant has both auditory and vestibular abnormalities from a mutation in this gene.

Reichert's cartilage - pharyngeal ach 2 cartilage, named after Karl Bogislaus Reichert (1811 - 1883) a German anatomist.

Reissner's membrane - (vestibular membrane, vestibular wall) is a membrane located inside the cochlea separating the scala media from scala vestibuli. Named after Ernst Reissner (1824-1878) a German anatomist. It primarily functions as a diffusion barrier, allowing nutrients to travel from the perilymph to the endolymph of the membranous labyrinth.

rhombomere -

Saccular macula -

Saccule - (Latin, sacculus = a small pouch)

sacculocollic reflex -

scala tympani - one of the three Cochlea cavities, it is filled with perilymph.

Scarpa's ganglion - (vestibular ganglion) primary afferent vestibular neuron ganglion of the vestibular nerve. Located within the internal auditory meatus.

semicircular canals - series of fluid-filled loops of the inner ear required for balance and sensing acceleration.

sensorineural - term used to describe one of the two major classes of hearing loss involving the central pathway from the cochlear (other form is conductive loss).

space of Nuel - within the cochlea, an organ of Corti space between the outer pillar cells and the phalangeal and hair cells. Named after Jean-Pierre Nuel (1847-1920) a Belgian ophthalmologist.

spiral ganglion neurons - (SGN) innervate the inner (Type I) and outer (Type II) hair cells of the cochlea.

stapedius muscle - (innervated by CN VII tympanic branch) one of the two muscles in the middle ear, contraction of this muscle pulls the stapes and dampens auditory ossicle movement.

stapes - (stirrup) a middle ear auditory ossicle (bone).stapes footplate - startle response -

stereocilia -finger-like projections from the apical surface of sensory hair cells forming the hair bundle in the cochlea. Formed by tightly cross-linked parallel actin filaments in a paracrystalline array with cell surface specializations (tip links, horizontal top connectors, and tectorial membrane attachment crowns).

stratified squamous epithelia - classification of epithelium which transiently forms a plug in external ear canal to the outer eardrum.

stria vascularis - forms the outer wall of the cochlear duct of the mammalian cochlea is composed primarily of three types of cells. Marginal cells line the lumen of the cochlear duct and are of epithelial origin. Basal cells also form a continuous layer and they may be mesodermal or derived from the neural crest. Intermediate cells are melanocyte-like cells, presumably derived from the neural crest, and are scattered between the marginal and basal cell layers. The stria forms endolymph and also contains a rich supply of blood vessels.

sulcus -

synostotically - anatomically normally separate skeletal bones fused together.

tectorial membrane - extracellular matrix that cover the sensory epithelial hair cells of the organ of corti within the cochlea.

alpha-tectorin and beta- (TECTA, TECTB) major non-collagenous protein component of the tectorial membrane forming a striated-sheet matrix. Synthesized as glycosylphosphatidylinositol-linked, membrane bound precursors.

temporal bone -

tensor tympani - (innervated by CN V mandibular nerve) one of the two muscles in the middle ear, contraction of this muscle pulls the malleus and tenses the tympanic membrane, dampening auditory ossicle movement. The muscle arises from auditory tube (cartilaginous portion) and is inserted into the malleus (manubrium near the root).

teratogens - trilaminar embryo -

tonotopy - term describing the mapping along the tectorial membrane within the cochlea of the different sound frequencies.

tympanic cavity - tympanic membrane -Utricle -Vacuolization - Vesicle - vestibular apparatus - vestibular evoked myogenic potential (VEMP) test

vestibular ganglion - (Scarpa's ganglion) primary afferent vestibular neuron ganglion of the vestibular nerve. Located within the internal auditory meatus.

vestibular membrane - (Reissner's) extends from the spiral lamina to the outer wall and divides the cochlea into an upper scala vestibuli, a lower scala tympani.

Vestibulocochlear Nerve - Cranial Nerve VIII

Whirlin - A PDZ scaffold protein expressed in hair cells at the stereocilia tips, essential for the stereocilia elongation process. The DFNB31 gene mutations cause hearing loss in human and mouse. This protein can interact with membrane-associated guanylate kinase (MAGUK) protein, erythrocyte protein p55 (p55).

Wnt7a - signaling through the Wnt pathway regulates the development of hair cell unidirectional stereociliary bundle orientation.


Webpage Terms

altricial animal - Term used to describe an animal born in a helpless state, with incomplete development of sensory systems at birth. For example rats and mice are born with incomplete development of visual and auditory systems. (More? [../OtherEmb/Rat.htm Rat Development] | [../OtherEmb/Mouse.htm Mouse Development] | [../OtherEmb/EmbHome.htm Other Embryos])

ampulla - Term used to describe an anatomical dilation of a tube or canal lumen. Anatomical description of the opening end of the uterine tube lying above the ovary and the enlarged initial segmeny of the semicircular canals of the inner ear vestibular system. (More? [ear6.htm Inner Ear] | [genitalXXuterus.htm Genital System - Female Uterus])

aneurism - (Greek, aneurysma = a widening, aneurysm) A term used to describe an abnormal widening of a vessel or anatomical tubal structure. (More? [../heart%2019.htm Blood Vessel])

aquaeductus vestibuli - see vestibular aqueduct

auditory neuropathy - (AN) abnormality of transmission of sound information to the brain.

Auditory tube – (eustachian tube) between the middle ear and oral cavity, has a bony (tympanic 1/3) and cartilaginous (pharyngeal 2/3) portion. The main role is equalization of pressure and fluid drainage in the middle ear.

auricular hillock - see hillock

atresia – narrowing, usually of an anatomical tube or cavity.

Autophagocytosis – (Greek, auto = self, phagy = eating, also called autophagy) a cell death mechanism that uses the cell’s own lysosomes to self digest.

Border cells - columnar cells within the organ of Corti on the medial portion of the basilar membrane.

canalis reuniens – (ductus reuniens, canaliculus reuniens, canalis reuniens, Hensen's canal, Hensen's duct, uniting canal, canalis reuniens of Hensen) short narrow canal connecting the cochlea duct to the saccule. (Victor Hensen, 1835-1924)

Cerumen - (ear wax) produced by glands in the skin of the outer portion of the ear canal.

Chondrified – the developmental differentiation of cartilage from mesenchye, an embryonic connective tissue.

cristae ampullaris – located in the ampulla of the membranous semicircular canals a region with both supporting and hair cells. The hair cell cilia are embedded in the gelatinous cupula.

Claudius cells - (cells of Claudius) columnar cells with microvilli overlying the basilar membrane and extend from Hensen's cells to the spiral prominence. Barrier cells that lie external to the organ of corti in endolymph.

Cochlear sac – embryonic structure, which will form the coiled cochlear duct and contribute to the saccule.

cochlear aqueduct - a bony channel containing the fibrous periotic duct. It connects the basal turn of the cochlea perilymphatic space with the subarachnoid space of the posterior cranial cavity.

Cochlin - major constituent of the inner ear extracellular matrix.

Collagen type II - major constituent of the inner ear extracellular matrix.

Conductive loss - term used to describe one of the two major classes of hearing loss involving external and middle ear abnormalities (other form is Sensorineural loss).

Connexins - channel proteins of the gap junctions that allow rapid communication between adjacent cells. The two connexins Cx26 and Cx30 are the major proteins of cochlear gap junctions.

Connexin 26 - A strikingly high proportion (50%) of congenital bilateral nonsyndromic sensorineural deafness cases have been linked to mutations in the GJB2 coding for the connexin26 {Inoshita, 2008 #1880}

cupular deposits - basophilic material on the cupulae of the semicircular ducts, an postnatal ageing phenomenon seen in some vestibular labyrinth.

clinical weeks – taken from last menstrual period (LMP) and therefore approximately two weeks before fertilization occurs.

Deiters' cells

Discoidin domain receptor 1 - (DDR1) a tyrosine kinase receptor activated by native collagen, expressed in the basement membrane and with fibrillar collagens. Found in basal cells of the stria vascularis, type III fibrocytes, and cells lining the basilar membrane of the organ of Corti. {Meyer zum Gottesberge, 2008 #1877}

ductus utriculosaccularis -

endochondral ossification – the process of bone formation from a pre-existing cartilage template.

Endoderm – endolymphatic fluid

endolymphatic sac - inner ear structure that has anatomically both an intraosseous and extraosseous component. Th e sac has functions regulating endolymph that are both secretory and absorptive. Also the site of endolymphatic sac tumors either sporadical occurring or associated with the autosomal-dominant von Hippel-Lindau (VHL) disease, due to a germ line mutation.

embryological weeks - taken from the time of fertilization which typically occurs around the middle (day 14), or just after, of the typical 28 day menstrual cycle.

Emx2 - homeobox gene affecting middle ear and inner ear development. {Rhodes, 2003 #1918}

Eustachian tube - (auditory tube) A cavity linking the pharynx to the middle ear, which develops from the first pharyngeal pouch. Named after Bartolomeo Eustachi (1500 - 1574) an Italian anatomist.

external auditory meatus - (ear canal) develops from the first pharyngeal cleft.

Ear wax – see cerumen.Epithelia –

espins – calcium-resistant actin-bundling proteins enriched in hair cell stereocilia and sensory cell microvilli and spiral ganglion neurons (SGNs)

eustachian tube – (auditory tube) between the middle ear and oral cavity, equalization of pressure in the middle ear.

external auditory canal –

fenestra ovalis - (oval window) separates the tympanic cavity from the vestibule of the osseous labyrinth.

fenestra rotunda - (round window) separates the tympanic cavity from the scala tympani of the cochlea.

fetus – (foetus) term used to describe human development after the 8th week (10th clinical week, LPM) and covers the developmental periods of second and third trimester.

fibroblast growth factor 1 – (Fgf-1) a growth factor released from cochlea sensory epithelium which stimulates spiral ganglion neurite branching. {Aletsee, 2003 #1924}

fibroblast growth factor 8 – (Fgf-8) a growth factor released by inner hair cells which regulates pillar cell number, position and rate of development. {Jacques, 2007 #1956}

fibroblast growth factor receptor 3 - (Fgfr-3) a tyrosine kinase receptor with a role in the commitment, differentiation and position of pillar cells in the organ of corti {Mueller, 2002 #1928}

fundamental frequency – (natural frequency) the lowest frequency in a harmonic series, for the female voice this is about 225 Hz.

Helicotrema – term used to describe the cochlear apex.

Hes – (hairy and enhancer of split) family of factors, which has been shown to be a general negative regulator of neurogenesis {Zheng, 2000 #1936}.

Hillock – a small hill, used to describe the six surface elevations on pharyngeal arch one and two.

Hindbrain – Invaginate -

Incus - (anvil) auditory ossicle

inner phalangeal cells

inner pillar cells – organ of Corti cells arranged in rows and form a boundary between the single row of inner hair cells and three rows of outer hair cells. These cells have surface-associated microtubule bundles {Henderson, 1995 #1950}.

inner sulcus - area of the cochlear duct

interdental region -

internal auditory meatus - (internal acoustic meatus, IAM) Anatomical canal in which CN VII and CN VIII ganglia reside and pass through to the brainstem. This bony canal lies between the posterior surface of the petrous pyramid and the bony labyrinth within the dense petrous bone. Also associated clinically with the site where acoustic neuromas may occur. (More? [../ear6.htm Hearing Development - Inner Ear])

Kölliker's organ - (Köllicker’s organ, greater epithelial ridge) Developing cochlear structure consisting of columnar-shaped supporting cells filling the inner sulcus and lying directly under the tectorial membrane. This transient organ regresses and generates the space of the inner sulcus. Rudolph Albert von Kolliker (1817-1905)??

lateral semicircular duct - Limbus –

LMP – acronym for last menstrual period, used to clinically measure gestation.

Malleus – (hammer) auditory ossicle

mastoid process - of temporal bone

Math1 - homolog of the Drosophila proneural gene atonal, necessary and sufficient for the production of hair cells in the mouse inner ear. {Chen, 2002 #1932}Negatively regulated by Hes1 and Hes5

meatal plug – temporary blockage of the external auditory meatus which forms at the end of the embryonic period and remains present until the seventh month.

meatus – anatomical opening, cavity or space (external acoustic meatus,internal auditory meatus)

Meckel’s cartilage – first pharyngeal ach cartilage, located within the mandibular prominence. This cartilage first appears at stage 16, stage 20 the beginning of membranous ossification. Named after Johann Friedrich Meckel, (1781 - 1833) a German anatomist. (http://www.whonamedit.com/doctor.cfm/1840.html)

membranous labyrinth - Mesenchyme - Mesoderm - Microtia - Modiolus –

Mucopolysaccharidosis - (MPS IIIB, Sanfilippo Syndrome type B) abnormality caused by a deficiency in the lysosomal enzyme N-acetyl-glucosaminidase (Naglu). Children with MPS IIIB develop abnormal hearing, and mental functioning culminating in early death.

Netrin-1 – secreted growth factor, expressed in the organ of Corti and spiral ganglion cells, role in process outgrowth.

neural tube –

olivocochlear – brainstem cholinergic and GABAergic efferent system that innervates sensory cells and sensory neurons of the inner ear.

organ of Corti – organ of Corti protein II - (OCP-II) cytosolic protein or transcription factor?

otolithic membrane - extracellular matrix that cover the sensory epithelia of the inner ear.

Ossicle – (small bone) the individual bone of the three middle ear bones (auditory ossicles), which reduce vibrational amplitude but increase force to drive fluid-filled inner ear.ossify – otic capsule – otic cupotic placode – otic vesicle –

Otoconin - inner ear biominerals required for vestibular apparatus function.

Otogelin – (Otog) an inner ear specific glycoprotein expressed in cochlea cells at different developmental times.

otolithic membrane – a membrane within the utricle and saccule containing embedded hair cell cilia and small crystalline bodies of calcium carbonate (otoliths). Functions to detect head motion.

Otoliths - small crystalline bodies of calcium carbonate found within the otolitic membrane of the utricle and saccule.

Ototoxic – compound or drug causing temporary or permanent hearing loss.

Outer hair cells – (OHCs) three rows of hair cells that function to increase basilar membrane motion through a local mechanical feedback process within the cochlea, the “cochlear amplifier”.

outer pillar cells - arranged in rows and form a boundary between the single row of inner hair cells and three rows of outer hair cells.

paratubal musculature – muscles lying beside the auditory (Eustachian) tube. The tensor veli, palatini (TVP) and tensor tympani muscles.

perilymph – perilymphatic space – Periotic Capsule - petrous portion - of temporal bone

pejvakin gene - in humans, two missense mutations in this gene cause nonsyndromic recessive deafness (DFNB59) by affecting the function of auditory neurons. {Schwander, 2007 #1883}

pharyngeal archpharyngeal pouchpharyngeal membranePharynx

Pillar cells – (PC) form an inner and outer row of support cells that form a boundary between inner and outer hair cells.

Placode

Preyer reflex – ear flick in mouse in response to sound.

presbyacusis

Prestin – a motor protein structurally similar to the anion transporter family expressed in cochlear outer hair cells.

Preauricular Tag - skin tags located in front of the external ear opening, are common in neonates and in most cases are normal, though in some cases are indicative of other associated abnormalities.

Primordium-

protocadherin 15 - (Pcdh15) required for initial formation of stereocilia bundles and changes in the actin meshwork within hair cells. The Ames waltzer (av) mouse mutant has both auditory and vestibular abnormalities from a mutation in this gene.

Reichert’s cartilage – pharyngeal ach 2 cartilage, named after Karl Bogislaus Reichert (1811 - 1883) a German anatomist.

Reissner's membrane - (vestibular membrane, vestibular wall) is a membrane located inside the cochlea separating the scala media from scala vestibuli. Named after Ernst Reissner (1824-1878) a German anatomist. “It primarily functions as a diffusion barrier, allowing nutrients to travel from the perilymph to the endolymph of the membranous labyrinth.”

Rhombomere -Saccular macula - Saccule – (Latin, sacculus = a small pouch)sacculocollic reflex –

scala tympani – one of the three Cochlea cavities, it is filled with perilymph.

Scarpa's ganglion – (vestibular ganglion) primary afferent vestibular neuron ganglion of the vestibular nerve. Located within the internal auditory meatus.

semicircular canals – series of fluid-filled loops of the inner ear required for balance and sensing acceleration.

Sensorineural – term used to describe one of the two major classes of hearing loss involving the central pathway from the cochlear (other form is conductive loss).

space of Nuel – within the cochlea, an organ of Corti space between the outer pillar cells and the phalangeal and hair cells. Named after Jean-Pierre Nuel (1847-1920) a Belgian ophthalmologist.

spiral ganglion neurons - (SGN) innervate the inner (Type I) and outer (Type II) hair cells of the cochlea.

stapedius muscle - (innervated by CN VII tympanic branch) one of the two muscles in the middle ear, contraction of this muscle pulls the stapes and dampens auditory ossicle movement.

stapes – (stirrup) a middle ear auditory ossicle (bone).stapes footplate - startle response -

stereocilia –finger-like projections from the apical surface of sensory hair cells forming the hair bundle in the cochlea. Formed by tightly cross-linked parallel actin filaments in a paracrystalline array with cell surface specializations (tip links, horizontal top connectors, and tectorial membrane attachment crowns).

stratified squamous epithelia – classification of epithelium which transiently forms a plug in external ear canal to the outer eardrum.

stria vascularis – forms the outer wall of the cochlear duct of the mammalian cochlea is composed primarily of three types of cells. Marginal cells line the lumen of the cochlear duct and are of epithelial origin. Basal cells also form a continuous layer and they may be mesodermal or derived from the neural crest. Intermediate cells are melanocyte-like cells, presumably derived from the neural crest, and are scattered between the marginal and basal cell layers. The stria forms endolymph and also contains a rich supply of blood vessels. (2612372)

sulcus –

synostotically – anatomically normally separate skeletal bones fused together.

tectorial membrane - extracellular matrix that cover the sensory epithelial hair cells of the organ of corti within the cochlea.

alpha-tectorin and beta- (TECTA, TECTB) major non-collagenous protein component of the tectorial membrane forming a striated-sheet matrix. Synthesized as glycosylphosphatidylinositol-linked, membrane bound precursors {Legan, 1997 #1865}

temporal bone –

tensor tympani - (innervated by CN V mandibular nerve) one of the two muscles in the middle ear, contraction of this muscle pulls the malleus and tenses the tympanic membrane, dampening auditory ossicle movement. The muscle arises from auditory tube (cartilaginous portion) and is inserted into the malleus (manubrium near the root).

teratogens – trilaminar embryo -

tonotopy – term describing the mapping along the tectorial membrane within the cochlea of the different sound frequencies.

tympanic cavity - tympanic membrane -Utricle -Vacuolization – Vesicle – vestibular apparatus – vestibular evoked myogenic potential (VEMP) test

vestibular ganglion - (Scarpa's ganglion) primary afferent vestibular neuron ganglion of the vestibular nerve. Located within the internal auditory meatus.

vestibular membrane - (Reissner’s) extends from the spiral lamina to the outer wall and divides the cochlea into an upper scala vestibuli, a lower scala tympani.

Vestibulocochlear Nerve - Cranial Nerve VIII

Whirlin - A PDZ scaffold protein expressed in hair cells at the stereocilia tips, essential for the stereocilia elongation process. The DFNB31 gene mutations cause hearing loss in human and mouse. This protein can interact with membrane-associated guanylate kinase (MAGUK) protein, erythrocyte protein p55 (p55).

Wnt7a – signaling through the Wnt pathway regulates the development of hair cell unidirectional stereociliary bundle orientation.


These notes introduce the development of hearing and balance and has links to further specific notes on the development of the auditory and vestibular system.

Due to its complex development, hearing is the most prone of all our senses to abnormal development and to be impacted upon by both genetic and environmental (materal) effects (More? [ear2.htm Hearing Abnormalities]).

In Australia within NSW, there is now an early postnatal analysis of neonatal hearing as part of a State Wide Infant Screening Hearing Program using AABR (More? [ear2.htm#neonatal_hearing_screening Neonatal Hearing Screening]).

If you have not studied hearing development before, there is a link to [../Science/ANAT2341lecture17.htm 2008 ANAT2341 Lecture 17 Hearing] and an earlier set of [#LectureSlides Science Lecture (2004)] slides on Hearing Development, an overview of developmental [#timing timing] and a text [#overview overview].