Development and Lineage Relationships of the Mouse Inner Ear

The functions of the inner ear are intimately dependent on its intricate three-dimensional structure and the mechanisms underlying its formation have been an area of active research interest. Recent advances in gene expression analyses and fate-mapping studies have provided some insights into this developmental process. The six sensory organs within the mouse inner ear and the neurons that innervate them are derived from a neural–sensory competent region at the otic cup stage. Notably, the neurons of the cochleovestibular (CV) nerve share a common lineage with two sensory organs, the maculae of the utricle and saccule. Within the sensory organs, hair cells can share a common lineage with supporting cells and even with nonsensory cells. Genetic fate-mapping studies also demonstrate contribution of neural crest cells to the mouse inner ear and trajectories of the cochlear and vestibular nerves to the sensory organs.