摘要：

The inner ear acts as the primary mediator for the sensations of hearing, balance and acceleration. Most of the structures within the inner ear develop from the oticplacodes, paired epithelial thickenings located adjacent to the developing hind brain. A key step in development of the inner ear is specification of identity along the main body axes at the otocyst stage. Recent advances have identified roles for the Hedgehog, Wnt and Retinoic acid signaling pathways in this process. The anterior ventral region of the otocyst contains neurosensory progenitor cells that will develop as both the neurons that form the VIII th cranial nerve and the sensory structures within the ear itself. Each sensory structure within the inner ear contains a mosaic of mechanosensory hair cells, a unique type of sensory cell, and supporting cells, a non-sensory cell type that provides trophic and structural support to the hair cells. The development of this mosaic utilizes a highly conserved signaling cassette which includes bHLH transcription factors and the Notch signaling pathway. Through positive and inhibitory interactions, subsets of cells within the developing mosaics are specified as either hair cells or supporting cells.

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