Roles of beta-catenin in inner ear development in rat embryos

We studied the roles of beta-catenin in inner ear development in rat embryo s using immunostaining and antisense experiments. High levels of beta-caten in appeared transiently in the otic cup during inner ear development. While beta-catenin accumulation was not yet observed in the thickened surface ec toderm at the otic placode, it became to be detected at the apical surface of the otic cup. Then it disappeared from the otocyst. When embryos were tr eated with the beta-catenin antisense oligodeoxynucleotide (ODN), accumulat ion of beta-catenin in the otic cup was suppressed and the beta-catenin pro tein level was significantly less in treated embryos than in controls. The number of cells in the otic cup in treated embryos was smaller than in cont rol embryos. Cells that incorporated bromodeoxyuridine (BrdU) in the otic p lacode were fewer in number in treated embryos than in controls. In control embryos, acoustic neurons were detected by 2H3 (anti-neurofilament 165 kDa antibody) staining within the acoustic neural crest complex, while only a little staining of 2H3 was observed in the complex of the treated embryos. These results suggested that beta-catenin plays a role in cell proliferatio n in the otic placodes and in differentiation of acoustic neurons within th e acoustic neural crest complex.