Figure 6.

The RA pathway is induced shortly after hair cell loss in the inner ear. A–C, Coronal sections of the posterior macula show expression patterns of aldh1a3 (A), cyp26b1 (B), and rarga (C) in the inner ear of 4.5-d-old larvae. aldh1a3 is expressed specifically in the anterior domain of the posterior macula, whereas cyp26b1 is expressed in the posterior domain. The rarga receptor is strongly expressed throughout the sensory patch. D–K, Coronal sections of the lateral crista. aldh1a3 is expressed in the lateral domain (D), low expression of cyp26b1 is found in the medial domain in wild-type larvae (E), and rarga is expressed throughout the crista (F). Expression of aldh1a3, cyp26b1, and rarga is induced at 24 hpa in the lateral crista (G–I), whereas sox2 is downregulated at 4 hpa (J, K). In situ hybridization was performed in tg(brn3c:mGFP) larvae, and hair cells are immunolabeled in green. Scale bars: A, D, 20 μm.