Whole-mount analysis of axonal projections. Multiple defects in cranial nerve projections are detected in severely affected embryos. (A) wild-type E10.5 embryo. The right (B) and the left (C) side of a E10.5 mutant embryo. (D–F) Enlargement of cranial nerve IX–XII region from B and C. Note the isolated ganglionic mass (asterisk in D) at the position of the ninth ganglion, the abnormal projection of a single nerve fiber toward the hindbrain (D) and the abnormal axonal bundles (asterisk in E,F) on both sides of the hindbrain. Note the extensive fusion of nerve IX and X on the left side of the animal (arrowhead in F). (G,H) Enlargement of the oculomotor nerve (III) region in B and C. Note the abnormal projection of nerve III on the left side (asterisk in H). (III) Oculomotor nerve; (V) trigeminal ganglion; (VII) facial ganglion; (IX) glossopharyngeal ganglion; (X) vagus ganglion; (XI) accessory ganglion; (XII) hypoglossal nerve. (A–C) Bar, 100 μm; (E–H) bar, 50 μm; (D) bar, 20 μm.