Fig. 2. Caudal hindbrain possesses a graded nonpermissive/repulsive activity for the cC-VC axons. (A,B) Two types of grafting experiments. The positions of the grafts were approximately 1.2 mm (A) and 1.8 mm (B) caudal to gVIII, respectively. Almost all cC-VC axons stalled or turned away before entering the graft in B (n=12), whereas a small proportion of the cC-VC axons still grew through the graft in A. (C) A piece of rostral hindbrain along the cC-VC path was cut and put back as control. Majority of cC-VC axons could grow through the graft (n=10). All grafts were soaked in DiO before transplanting into the hosts, thus the borders of the grafts were discerned by DiO signal combined with bright-field illumination. DiO signal was displayed only in C, but removed for better illustration of axons in the grafts in other images. White dots outline the border of grafts in A-C. (D) Quantification of the percentage of axons entering the graft (^*P<0.0001, Mann-Whitney U test) (error bar indicates s.d.). Scale bar: 400 µm.