Fig. 5. Axon-axon interactions strongly influence retinotectal pathfinding. (A) Transplants yield GFP-expressing donor RGCs in host eyes. (B-E) Dorsal views, 5 dpf, rostral upwards. Donor axons labeled with brn3c:GFP; pathfinding errors indicated by yellow stars. (B'-E') Error quantitation. (B,B') In wild-type> wild-type transplants, donor axons pathfind perfectly. (C,C') By contrast, when transplanted into ast hosts, wild-type axons make significantly more errors. (D,D') As expected, ast donor axons make many errors in ast hosts. (E,E') However, when transplanted into wild-type hosts, ast axons make significantly fewer errors. Scale bar: 50 µm.