Zoomed-in views of boxed areas in Figure 6 showing fibers at midline crossing and at the contralateral site. (A,B) E13.5(+1 DIV); (C,D) E14.5(+1 DIV); (A,C) control treatment with PBS; (B,D) test treatment with ChABC. At E13.5 in PBS, fibers advanced as fascicles normal to the the midline. At E13.5(+1 DIV) in ChABC, a subpopulation of unfasciculated fibers projected normal to the midline and crossed to the contralateral side but others deviated from the normal trajectories. At E14.5(+1 DIV) in ChABC, most fibers made the anterior turn but some unfasciculated fibers (arrows) failed to make the turn.. The dashed line indicates the midline, and dotted lines the rhombomerre boundaries. Scale bar: 100 μm.