Figure 3. Failure of marginal cell maturation in Tbx1^nmf219 mutant mice.

Transverse sections through the cochlear ducts of a +/+ control mouse (A) and a Tbx1^nmf219 mutant mouse (B) at P3, stained with H&E. The boxed region of A encloses the stria vascularis and is enlarged in C, and the similarly positioned boxed region of B is enlarged in D. The +/+ control mouse (A) has a normally developed a stria vascularis (sv), but a mature stria vascularis does not form in Tbx1^nmf219 mutant mice (B). The arrow in C points to the layer of mature marginal cells (mc) in the stria vascularis of the +/+ control mouse, which have interdigitated with the overlying intermediate cells. The arrow in D points to the layer of precursor epithelial cells (ec) lining the scala media (SM) in the Tbx1^nmf219 mutant mouse, which have not matured into marginal cells and do not interdigitate with intermediate cells. For orientation Reissner’s membrane (rm) is marked in A and B.