Fig. 8. Tbx1^–/– inner ear and VIIIth ganglion morphology at E13.5. (A-D,F,G,J,K) Transverse sections through wild-type and Tbx1^–/– ears/ganglia at E13.5, reacted with mAb2H3 (anti-neurofilament) and counter-stained with Cresyl Violet. Axes in F apply to all except G. Red arrows in A and C indicate regions of vestibular (vest) neuronal cytology and cyan arrows in C auditory (aud) neuronal cytology. The distinguishing cytological features (nuclear size and basophilia) from a mutant posterior ganglion are shown at high magnification in G, with vestibular neuronal cytology shown at right. White asterisks in A and B indicate a branch of the facial nerve. Section shown in F passes through a Tbx1^–/– posterior compound ganglion and epithelial posterior pole. Pvest, presumptive vestibular ganglion; Paud, presumptive auditory ganglion. Brackets and arrowheads in J and K indicate cellular stratification. Scale bars: in D, 60 µm for A-D; 20 µm for J,K. (E) 3-D reconstructions of serial sections reacted as described above. Presumptive vestibular (red) and auditory (cyan) ganglion tissue is shown in relation to the inner ear epithelium. c, cochlea; sa, superior ampulla; la, lateral ampulla; pa, posterior ampulla; sc, superior canal; lc, lateral canal; pc, posterior canal; ed/es, endolymphatic duct/sac; u, utricle; s, saccule; lt, lateral tube; ms, medial sac; dp, dorsal projection. (H) Double immunolabeling with mAb2H3 and anti-MATH1 shows neurites (in green, arrowheads) enveloping the base of a MATH1-positive cell. Dotted line indicates the basement membrane. (I) Anteroventrolateral view of the Tbx1^–/– inner ear; the region of stratification and innervation is mapped in brown. Approximate section levels are indicated. (L) MATH1-positive nuclei occupy an apical position in the epithelium. Dashed line indicates the lumen, which is collapsed. Dotted line indicates the basement membrane.