Document Detail

The differential sensitivities of inner ear structures to retinoic acid during development.
MedLine Citation:
PMID:  9851848     Owner:  NLM     Status:  MEDLINE    
In order to examine the mechanisms that underlie development of the inner ear, the normal processes were perturbed using all-trans-retinoic acid (RA). By implanting a resin exchange bead saturated with RA into stage 16 (Hamburger and Hamilton, 1951, J. Morphol. 88, 49-92) embryonic day 2.5 chick ears, it was possible to analyze its in vivo effects on inner ear development. There is a temporal window during which the developing chick inner ear is particularly susceptible to the effects of RA (stages 16-19). This RA period of sensitivity precedes evidence of gross morphologic or histologic differentiation by at least 24 h, suggesting that mechanisms controlling formation of key inner ear structures are already in progress. There is a dose dependence on RA, with increasing doses of RA generating increasingly severe phenotypic abnormalities. Data indicate that these effects are due to differential sensitivities of the various inner ear structures to RA during their formation. In general, the vestibular structures were more susceptible to RA effects than the cochlear duct. Furthermore, nonsensory structures such as semicircular canals seemed to display a greater susceptibility to RA than their associated sensory structures (i.e., cristae). Among the three semicircular canals, the superior canal was the most susceptible to RA treatment, whereas the common crus was particularly resistant, suggesting that the molecular mechanisms for each structure's formation are different. The defect in semicircular canal formation is due to problems in the initial outgrowth of the canal plate which in turn is related to a down-regulation of early otocyst cell proliferation. This perturbation model provides valuable insight into the processes involved in producing the intricate patterning of the inner ear.
D Choo; J L Sanne; D K Wu
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Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  Developmental biology     Volume:  204     ISSN:  0012-1606     ISO Abbreviation:  Dev. Biol.     Publication Date:  1998 Dec 
Date Detail:
Created Date:  1999-01-27     Completed Date:  1999-01-27     Revised Date:  2005-11-17    
Medline Journal Info:
Nlm Unique ID:  0372762     Medline TA:  Dev Biol     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  136-50     Citation Subset:  IM    
Laboratory of Molecular Biology, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Rockville, Maryland, 20850, USA.
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MeSH Terms
Apoptosis / drug effects
Cell Differentiation / drug effects
Chick Embryo
Dose-Response Relationship, Drug
Ear, Inner / cytology,  drug effects,  embryology*,  physiology*
Keratolytic Agents / pharmacology
Tretinoin / pharmacology,  physiology*
Reg. No./Substance:
0/Keratolytic Agents; 302-79-4/Tretinoin

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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