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Competence, specification and commitment in otic placode induction

Groves, Andrew K. and Bronner-Fraser, Marianne (2000) Competence, specification and commitment in otic placode induction. Development, 127 (16). pp. 3489-3499. ISSN 0950-1991.

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The inner ear is induced from cranial ectoderm adjacent to the hindbrain. Despite almost a century of study, the molecular mechanisms of inner ear induction remain obscure. We have identified four genes expressed very early in the anlage of the inner ear, the otic placode. Pax-2, Sox-3, BMP-7 and Notch are all expressed in placodal ectoderm from the 4-5 somite stage (ss) onwards, well before the otic placode becomes morphologically visible at the 12-14ss. We have used these four molecular markers to show that cranial ectoderm becomes specified to form the otic placode at the 4-6ss, and that this ectoderm is committed to a placodal fate by the 10ss. We also demonstrate that much of the embryonic ectoderm is competent to generate an otic placode if taken at a sufficiently early age. We have mapped the location of otic placode-inducing activity along the rostrocaudal axis of the embryo, and have determined that this activity persists at least until the 10ss. Use of the four molecular otic placode markers suggests that induction of the otic placode in birds occurs earlier than previously thought, and proceeds in a series of steps that are independently regulated.

Item Type:Article
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URLURL TypeDescription
Bronner-Fraser, Marianne0000-0003-4274-1862
Additional Information:Copyright © 2000 by Company of Biologists. Accepted 4 June 2000; published on WWW 20 July 2000. We thank Julian Lewis, David Ish-Horowicz, Domingos Henrique, Brian Huston and Hisato Kondoh for cDNA probes. A.K.G. wishes to thank Clare Baker for her support and advice, and for her comments on the manuscript, Heather Etchevers for advice on the paraffin in situ protocol and Butch Welch for assistance with color image processing. A.K.G. is supported by the House Ear Institute and an NIH Small Project Grant, DC03630-01. This work was also supported by NIH grants NS 13815 and NS 36585 to M.B.-F.
Funding AgencyGrant Number
House Ear InstituteUNSPECIFIED
NIHNS 13815
NIHNS 36585
Subject Keywords:Otic Placode, Induction, Chicken, Competence, Specification, Commitment
Issue or Number:16
Record Number:CaltechAUTHORS:GROdev00
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:12782
Deposited By: Archive Administrator
Deposited On:23 Dec 2008 18:01
Last Modified:03 Oct 2019 00:31

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