Difference between revisions of "Sensory - Balance Development"

From Embryology
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==Embryonic Inner Ear Labyrinth==
 
==Embryonic Inner Ear Labyrinth==
===Week 4===
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===Week 5===
  
 
[[File:Stage13 otocyst.jpg|600px|Stage 13 otocyst]]
 
[[File:Stage13 otocyst.jpg|600px|Stage 13 otocyst]]

Revision as of 12:21, 28 April 2011

Gray0924.jpg

Introduction

The sensory system for balance arises as part of the inner ear development from the otic placode then otic vesicle. Three flattened pouch of epithelium extend from the otic vesicle from which the final semicircular canals will be fashioned. During early development the epithelia of two apposing wall of the pouch approach each other and form a fusion plate, that clears to form a hole generating the loop of the remaining tissue as semicircular canals. Fusion plate clearing has been suggested to occur due to both apoptosis and epithelial-mesenchymal transition.[1]

The adult semicircular canals are fluid-filled tubules that are arranged perpendicularly to each other in inner ear and remain connected to the cochlea. This tubular arrangement and connection allows fluid movement and detection of head movement in all 3 planes.

Vestibular labyrinth cartoon[2]
Hearing Links: Introduction | inner ear | middle ear | outer ear | balance | placode | hearing neural | Science Lecture | Lecture Movie | Medicine Lecture | Stage 22 | hearing abnormalities | hearing test | sensory | Student project

  Categories: Hearing | Outer Ear | Middle Ear | Inner Ear | Balance

Historic Embryology - Hearing 
Historic Embryology: 1880 Platypus cochlea | 1892 Vertebrate Ear | 1902 Development of Hearing | 1906 Membranous Labyrinth | 1910 Auditory Nerve | 1913 Tectorial Membrane | 1918 Human Embryo Otic Capsule | 1918 Cochlea | 1918 Grays Anatomy | 1922 Human Auricle | 1922 Otic Primordia | 1931 Internal Ear Scalae | 1932 Otic Capsule 1 | 1933 Otic Capsule 2 | 1936 Otic Capsule 3 | 1933 Endolymphatic Sac | 1934 Otic Vesicle | 1934 Membranous Labyrinth | 1934 External Ear | 1938 Stapes - 7 to 21 weeks | 1938 Stapes - Term to Adult | 1940 Stapes | 1942 Stapes - Embryo 6.7 to 50 mm | 1943 Stapes - Fetus 75 to 150 mm | 1946 Aquaductus cochleae and periotic (perilymphatic) duct | 1946 aquaeductus cochleae | 1948 Fissula ante fenestram | 1948 Stapes - Fetus 160 mm to term | 1959 Auditory Ossicles | 1963 Human Otocyst | Historic Disclaimer

Some Recent Findings

  • Lmo4 in the vestibular morphogenesis of mouse inner ear[3] "Our results demonstrate that Lmo4 controls the development of the dorsolateral otocyst into semicircular canals and cristae through two distinct mechanisms: regulating the expression of otic specific genes and stimulating the proliferation of the dorsolateral part of the otocyst."
  • Saccular function and motor development in children with hearing impairments[4] "The purpose of this study was to evaluate saccular function in children with hearing impairments using the Vestibular Evoked Myogenic Potential (VEMP). The impact of the saccular hypofunction on the timely maturation of normal balance strategies was examined using the Movement Assessment Battery for Children (Movement ABC). ...No VEMP was evoked in two thirds of the hearing impaired (HI) children in response to the bone-conducted stimulus. Children who were reportedly hearing impaired since birth had significantly poorer scores when tested with the Movement ABC."
  • Orbital spaceflight during pregnancy shapes function of mammalian vestibular system.[5] "Pregnant rats were flown on the NASA Space Shuttle during the early developmental period of their fetuses' vestibular apparatus and onset of vestibular function. ...Taken together, these studies provide evidence that gravity and angular acceleration shape prenatal organization and function within the mammalian vestibular system."

Embryonic Inner Ear Labyrinth

Week 5

Stage 13 otocyst

Week 8

Stage 22 ear

Stage 22 ear

Inner Ear Labyrinth

Vestibular labyrinth (toadfish)
  • Cochlea - Otic vesicle - Otic placode (ectoderm)
  • Semicircular canals - Otic vesicle - Otic placode (ectoderm)
  • Saccule and utricle - Otic vesicle - Otic placode (ectoderm)

Cranial Nerve VIII

  • Auditory component - Otic vesicle and neural crest (ectoderm)
  • Vestibular component - Otic vesicle and neural crest (ectoderm)
  • 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.
Links: Inner Ear

Vestibular Nerve

Vestibular labyrinth cartoon.jpg

Semicircular Canal Development

Mouse - inner ear cartoon

A study using the chicken model suggests that an epithelial to mesenchymal transition occurs during early development of the semicircular canals.[6]

"Semicircular canals are sensory organs for balance, consisting of fluid-filled tubules that are arranged perpendicularly to each other in inner ear. The precise mechanism of the morphogenesis of this unique organ is still under investigation. Semicircular canals arise from the flattened pouch of epithelium. The centers of two apposing wall of the pouch approach each other and form a fusion plate. The clearing of the fusion plate makes a hole and leaves the remaining tissue as semicircular canals. Three mechanisms have been proposed for this clearing: programmed cell death, epithelial-mesenchymal transition, and retraction of the cells in the fusion plate to surrounding semicircular canals. Previous studies have revealed programmed cell death in the fusion plate, although other two hypotheses were not disproved. Here we examined the contribution of epithelial-mesenchymal transition and epithelial retraction to the morphogenesis of semicircular canals. We analyzed immunohistochemically the structural change in the epithelium of the developing fusion plate using molecular markers, basal lamina component laminin, cytoskeletal F-actin, and cellular junctional marker beta-catenin. Our observation revealed that fusion plate epithelium lost its apico-basal polarity and intermingled with facing fusion plate cells, associated with the disruption of basal lamina. Moreover, there were several cells with mesenchymal appearance adjacent to the torn basal lamina. We also found the merging of apposing basal laminae at the border between forming canal and breaking fusion plate. These observations suggest that the epithelial-mesenchymal transition, rather than the epithelial retraction, may be responsible for clearing fusion plate cells."[6]

References

  1. <pubmed>18648181</pubmed>
  2. <pubmed>19723316</pubmed>
  3. <pubmed>19913004</pubmed>
  4. <pubmed>20148080</pubmed>
  5. <pubmed>18298265</pubmed>
  6. 6.0 6.1 <pubmed>18648181</pubmed>


Reviews

Articles

  • Development of the mouse cochlea database (MCD). Santi PA, Rapson I, Voie A. Hear Res. 2008 Sep;243(1-2):11-7. Epub 2008 May 25. PMID:18603386 | PMC2628570
  • A mathematical model of human semicircular canal geometry: a new basis for interpreting vestibular physiology. Bradshaw AP, Curthoys IS, Todd MJ, Magnussen JS, Taubman DS, Aw ST, Halmagyi GM. J Assoc Res Otolaryngol. 2010 Jun;11(2):145-59. Epub 2009 Dec 1. PMID: 19949828

Search PubMed

May 2010 "Inner Ear Development" All (4027) Review (452) Free Full Text (750)

Search Pubmed: Balance Development | Vestibular Development |Semicircular Canal Development

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Cite this page: Hill, M.A. (2021, May 17) Embryology Sensory - Balance Development. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/Sensory_-_Balance_Development

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© Dr Mark Hill 2021, UNSW Embryology ISBN: 978 0 7334 2609 4 - UNSW CRICOS Provider Code No. 00098G