Fig. 6. Ncad is required for guidance of RGC axons. (A) Dorsal view of 4 dpf wild-type embryos labeled with diI (red) and diO (green) in the left and right eyes, respectively. RGC axons project to contralateral optic tectum. (B) Trajectories of diI/diO labeled RGC axons in pac^fr7. Retinal axons project to both ipsilateral and contralateral tecta. White arrowheads indicate mis-routed retinal axons. (C,D) Ventral view of 60 hpf diI/diO-labeled wild-type (C) and pac^fr7/rw95embryo (D). In pac^fr7/rw95, RGC axons change outgrowth direction by following retinal axons that come from the opposite eye (D, white arrowheads). (E,F) Expression of ath5:GFP in 3 dpf wild-type (E) and pac^fr7 embryos (F). In pac^fr7, retinal cells have migrated out from the optic cups and invaded the ventral brain (white arrowheads). There is variability in the phenotype and this embryo is more severe than most. (G-I) Three dpf chimaeric eyes in which pac^fr7 cells (green) were transplanted into wild-type embryos. Asterisks indicate retinal cells that escape from the eye cups. (H) Red indicates diI-labeled wild-type axons that bifurcate at ectopically positioned retinal cells (white arrowheads). (I) pac (green, GFP) and wild-type (red, diI) retinal axons (white arrowheads) turn in an inappropriate direction at the interface with retinal cells (white asterisk) and project to the telencephalon. (J) Three dpf wild-type embryos, in which pac^fr7 cells were transplanted to the retinae at 24 hpf. pac retinal axons adopt a normal contralateral trajectory. (K,L) Ventral view of 30 hpf wild-type (K) and pac^fr7 (L) forebrains labeled with a slit3 RNA probe. Arrows indicate three domains of slit3 expression, which bound the anterior commissure, post-optic commissure and the optic chiasm. AC, tract of anterior commissure; OC, position of optic chiasm; POC, post-optic commissure