The first steps towards hearing: mechanisms of otic placode induction.
The entire inner ear, together with the neurons that innervate it, derive from a simple piece of ectoderm on the side of the embryonic head the otic placode. In this review, we describe the current state of the field of otic placode induction. Several lines of evidence suggest that all craniofacial sensory organs, including the inner ear, derive from a common "pre-placodal region" early in development. We review data showing that assumption of a pre-placodal cell state correlates with the competence of embryonic ectoderm to respond to otic placode inducing signals, such as members of the fibroblast growth factor (FGF) family. We also review evidence for FGF-independent signals that contribute to the induction of the otic placode. Finally, we review recent evidence suggesting that Wnt signals may act after FGF signaling to mediate a cell fate decision between otic placode and epidermis.
Ohyama
Takahiro
T
Department of Cell and Molecular Biology, House Ear Institute, Los Angeles, CA, USA.
Groves
Andrew K
AK
Martin
Kareen
K
D000818:Animals; D002454:Cell Differentiation; D002642:Chick Embryo; D004423:Ear / Q000196:embryology*; D004475:Ectoderm / Q000502:physiology; D004627:Embryonic Induction; D005346:Fibroblast Growth Factors / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D018507:Gene Expression Regulation, Developmental; D006309:Hearing / Q000502:physiology*; D051379:Mice; D008954:Models, Biological; D015398:Signal Transduction; D051153:Wnt Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism
D051153:Wnt Proteins; D005346:Fibroblast Growth Factors