Figure 4. Manipulating Wnt activity alters inner ear sensory organ formation.

(a–a”) Whole-mount (tiled maximum projection) views of an E7 chicken inner ear electroporated at E2 with a control vector (T2-mEGFP) and immunostained for Sox2 (a’) and two hair cell markers, Myo7a and HCA (‘HC’ in all panels). (a”) All sensory organs are properly formed: posterior (pc), anterior (ac) and lateral (lc) cristae, saccule (sc), utricle (ut), basilar papilla (bp), and lagena (l). (b–c”) An inner ear transfected with T2-βcat-GOF. Note the absence of EGFP expression and severe defects in overall morphology of the vestibular system and basilar papilla; the remaining sensory patches are small and abnormally shaped (b’). (c–c”) Higher magnification of the vestibular Sox2-positive patches containing Myo7a and HCA-expressing hair cells. (d–f”) An inner ear transfected with T2-βcat-LOF. (d–d’’) Whole-mount (tiled maximum projection) views demonstrating the presence of numerous ectopic sensory patches with hair cells, and severe defects in inner ear morphology. (e-e’) Higher magnification of the dorsal region, where transfected cells form ectopic sensory patches positive for Sox2 (e’) and populated with Myo7a and HCA-expressing hair cells (arrowheads). (f–f”) In contrast, in ventral domains, EGFP-positive patches are devoid of Sox2 and hair cell markers expression. The only remaining Sox2-expressing patches are not transfected (arrows).