Fig. 1. Patterning and morphogenesis of the inner ear. Diagrams of the transformation of the otic vesicle into the mature structure of the inner ear. Early in development (left), the axes of the otic vesicle are patterned, with the presumptive vestibular system expressing Dlx5 and Hmx3 (red) and the developing cochlea expressing Otx2 (yellow). The lateral pouch is defined by expression of Otx1 (blue stipple). A few hours later, during morphogenesis, discrete regions in the dorsal and lateral pouch begin to transcribe netrin 1 (blue, middle). These regions will subsequently undergo fusion and disappear, leaving the epithelium in the perimeter to form the walls of the mature canals (right). Motion is detected by hair cells housed in swellings at the base of each canal called ampullae (^*). In all of the following figures, paintfilled inner ears are shown looking down onto the lateral canal, with anterior towards the right, whereas sections through the otic vesicle are in the transverse plane (as indicated by a broken line), with dorsal upwards and lateral towards the right.