Fig. 3. Shh neutralisation alters the distribution of RGC axons at the optic chiasm. (A-C) Ventral views of the proximal visual pathway from E18.5 non-injected (A) and from anti-Shh (B) and control IgG (C) hybridoma-treated mouse embryos visualised by complete DiI filling. Anterior is to the top. In anti-Shh-treated embryos, axons spread at the chiasm (large white arrows in B), and ipsilateral tract and contralateral nerve (small white arrow, compare with A) projections appear increased; growth cones accumulate along the path (yellow arrows). (D) Quantification of the width occupied by DiI-labelled fibres at the chiasm in untreated (n=6), control-treated (n=7) and anti-Shh-treated (n=11) embryos (^*P<0.05, ^**P<0.01, one-way ANOVA). (E) Schematic ventral view of the proximal visual system depicting fibre trajectory and Shh and SSEA-1 distribution in control (left) and anti-Shh-treated (right) embryos. (F,G) Confocal images of flat-mounted E18.5 ipsilateral retinas showing DiI retrograde labelling from the optic tract in control and anti-Shh-treated embryos. Arrows in G indicate the presence of abnormal retrograde labelling in quadrants other than VT. cot, contralateral optic tract; iot, ipsilateral optic tract; oc, optic chiasm; od, optic disc; on, optic nerve; ot, optic tract. Scale bar: 500 µm in A-C; 215 µm in F,G.