Developmental expression of the TGFβs in the mouse cochlea

Mice with targeted disruption of the TGFβ2 gene display defects in epithelial-mesenchymal tissue interactions in several tissues including the developing cochlea. Specifically, the region of the spiral limbus and the overlying interdental cells, structures putatively involved in endolymphatic fluid homeostasis, display morphogenetic abnormalities. These findings prompted us to explore the pre-natal and post-natal expression of all three mammalian TGFβ genes in the developing mouse inner ear. TGFβ2 mRNA expression was identified throughout the cochlear epithelium at all of the developmental stages examined. TGFβ3 mRNA expression was identified in the mesenchymal tissues of the cochlea surrounding the otic epithelium. We found no evidence for compensation by the other two TGFβ isoforms in the cochleas of the TGFβ2 mutants.