Figure 1. Cilia in the ventral region of the epithelial lining of the middle ear.

(a) A dissected right temporal bone illustrates the relative position of the Eustachian tube (ET), the inner ear (cochlea and vestibule), the middle ear cavity, and the tympanic membrane. The cryosection plane is denoted by the dashed line. The inner ear is on the other side the medial wall of the middle ear cavity and is dorsal to the Eustachian tube, while the tympanic membrane is on the lateral side of the middle ear cavity. The vestibular structure is dorsal to the cochlea in the inner ear. The orientation designations are: L-lateral; M-medial; V-ventral; D-dorsal; A-anterior; P-posterior. Scale: 2 mm. (b–g) Temporal bone cryosections staining with an antibody against acetylated α-tubulin (green) and phalloidin (red) for actin (b–f), or an antibody against Arl13b (green) and Hoechst for DNA (red) (g). Panels c-f represent the larger views of the boxed regions (a–d) in b, in the epithelium of the middle ear at the areas of the tympanic membrane (a), ventral regions near the ET (b) and (c), or in the ET (d). The ciliated areas consist of a lumen staining for acetylated α-tubulin that is enriched in the cilia axoneme. The ciliation pattern in the middle ear revealed by acetylated α-tubulin staining (b) was validated by Arl13B staining (g), which marks the axoneme. Scale (b,g): 200 μm.