Fig. 6. Aberrant axon pathfinding following r3 removal. Whole-mount anti-neurofilament staining at 20 hours (A-C), 30 hours (D-F), 45 hours (G) or 72 hours (H) after unilateral r3 removal. (A,D) dorsal views, (B,E,G,H) Operated side; (C,F) unoperated side. In each case, an aberrant axon projection was detected within r3* mesenchyme, between the trigeminal (gV) and facial (gVII) ganglia (arrow in A,B,D,E,G,H) and this ectopic cranial nerve grew thicker over time. (I) DiI injection into the ectopic nerve (45 hours after r3 removal) retrogradely labelled sensory neurones within the trigeminal ganglion (arrow) and facial ganglion (arrowhead), while within the hindbrain (J,K) longitudinal sensory axons were labelled, although motor cell bodies in r1/r2 and r4/r5 were not always labelled (J shows combined phase/DiI view of flatmounted hindbrain, K shows DiI view only). Lateral views of embryos after bilateral DiI injections into medial r2 (L,M) or medial r4 (N,O) 45 hours after r3 removal. Anterogradely labelled axons were rarely detected within the ectopic cranial nerve. f, facial nerve; m, mandibular branch of trigeminal nerve; OV, otic vesicle.