Fig. 7. Histology of inner ears of P12 Foxi1^+/+ and Foxi1^-/- mice. Nasal (N) and caudal (C) orientations as marked in A. In Foxi1^-/- mice the entire inner ear is enlarged with large irregular cavities in place of the delicate inner ear structures of the wild-type ear. S, saccule; U, utricle; ME, middle ear; asterisks mark the basal turn of the cochlea in A. (C) In the mutant the endolymphatic sac (ES) seems to compress the cerebellum and the posterior part of the ES (arrowheads) is expanded considerably in the posterior/dorsal direction (double headed arrow) compared with the wild type (A). The temporal bone (TB, arrowheads) is also clearly reduced. (B,D) The normal cochlea with its modiolus (Mo, in B) is absent in the mutant (D) and in its place is an enlarged cavity with an apical cyst (AC). Scale bars: in A, 100 µm for A,C; in B, 100 µm for B,D.