Some Recent Findings
Wilkinson AR, Jiang ZD. Brainstem auditory evoked response in neonatal neurology. Semin Fetal Neonatal Med. 2006 Dec;11(6):444-51. Epub 2006 Oct 2. Review.
Rodriguez-Vazquez JF. Development of the stapes and associated structures in human embryos. J Anat. 2005 Aug;207(2):165-73. "The objective of this study was to clarify the development of the stapes in humans and its relationship with the cartilage of the second branchial arch. The study was carried out in 25 human embryos between 6 and 28 mm crown-rump length. The stapes develops at the cranial end of the second branchial arch through an independent anlage of the cartilage of this arch. Between the stapedial anlage and the cranial end of the Reichert's cartilage there is a formation called the interhyale, the internal segment of which gives rise to the tendon of the stapedial muscle. 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."
Some Recent Findings
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; [Epub ahead of print] "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; [Epub ahead of print] ".. 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."
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)
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."
Barald KF, Kelley MW. From placode to polarization: new tunes in inner ear development. Development. 2004 Sep;131(17):4119-30. Review.
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 labrynth (otic capsule) chondrifies
Week 12-16 - Capsule adjacent to membranous labrynth 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 respone 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.
References
Molecular Normal Development
List of recent Ear Development Reviews
Recent Reviews Abnormal Development
- Webster
WS. [See
Related Articles] Teratogen update:
congenital rubella. Teratology. 1998 Jul;58(1):13-23.
Review. PMID: 9699240; UI: 98364396.
- 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.PMID: 9279630; UI: 97425580.
- 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. PMID: 8893214; UI:
97048378.
- 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. MID: 7747785; UI: 95266633.
- Strasnick
B, et al [See
Related Articles] Teratogenic hearing loss. J Am
Acad Audiol. 1995 Jan;6(1):28-38. Review. PMID: 7696676;
UI: 95210704.
- Kossowska
E, et al. [See
Related Articles] Prenatal and neonatal
prophylaxis in otorhinolaryngology. Int J Pediatr
Otorhinolaryngol. 1980 Jun;2(2):85-98. Review. PMID:
6765128; UI: 84160924.
- Gottlieb
G. [See
Related Articles] Conceptions of prenatal
development: behavioral embryology. Psychol Rev. 1976
May;83(3):215-34. Review. No abstract available.
PMID: 188059; UI: 77079452.
- 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.
Glossary of Terms
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Comments
Page under Development (notice removed when complete)
These notes introduce the molecular development of hearing and balance. Due to its complex development, hearing is the most prone of
all our senses to abnormal development and to be impacted upon by materal effects.
There is an additional page covering Hearing Abnormalities.
If you have not studied hearing development before, there is a set of Science Lecture (2004) slides on Hearing Development,
an overview of developmental timing and a text overview.
This first page introduces a broad overview of this sense, links on this page will take you to more specific information.
Please email Dr Mark Hill if you wish to make a comment about this current project.
