Fig. 12. In situ hybridization using probes for Foxi1, Pds, Coch and Jagged1 on inner ear sections from E16.5. (A) Foxi1 and Pds have similar expression patterns in wild-type endolymphatic duct/sac epithelium. At this developmental stage Foxi1 expression is restricted to the endolymphatic duct/sac epithelium. (B) On Foxi1^-/- inner ear sections (B) Pds expression is not detectable in the endolymphatic epithelium (right arrowhead) while it is expressed in the utricle (left arrowhead). Higher magnifications (on the right) of both Foxi1^+/+ and Foxi1^-/- epithelium also demonstrate a lack of Pds expression in Foxi1^-/- epithelium. (C) Pds is expressed (arrowheads) in the cochlea (top row) and in the epithelium adjacent to sensory areas of the utricle (bottom row) in both Foxi1^+/+ and Foxi1^-/- mice. (D) Coch expression is missing in the endolymphatic duct/sac epithelium in Foxi1^-/- animals (arrowheads) whereas the expression is unaffected in the common crus (CC). A typical punctate pattern is seen in wild-type endolymphatic duct/sac epithelium. (E) In spite of altered morphology, Coch is expressed in other inner ear structures such as cochlea (CO), saccule/utricle (SU) and ampulla (AM) in subepithelial cell layers in the Foxi1^-/- inner ear. (F) The expression in the cochlea also seems to be similar in Foxi1^+/+ and Foxi1^-/- mice. (G) In Foxi1^-/- inner ears Jagged1 expression is missing in the endolymphatic sac/duct epithelium (ED, arrowheads) but the expression is not affected in the utricle (U). In wild-type mice, Jagged1 has a punctate expression pattern in the endolymphatic duct/sac epithelium. (H) Jagged1 expression can be detected in the cochlea of both Foxi1^+/+ and Foxi1^-/- mice (arrowheads). Scale bars: 100 µm.

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