From placode to polarization: new tunes in inner ear development.

The highly orchestrated processes that generate the vertebrate inner ear from the otic placode provide an excellent and circumscribed testing ground for fundamental cellular and molecular mechanisms of development. The recent pace of discovery in developmental auditory biology has been unusually rapid, with hundreds of papers published in the past 4 years. This review summarizes studies addressing several key issues that shape our current thinking about inner ear development, with particular emphasis on early patterning events, sensory hair cell specification and planar cell polarity.