Fig. 7. Anterograde-labeled optic chiasms from wild-type, Brn3b^–/– and Brn3b/Brn3c-double mutant mice. At P2, DiI (red) was injected into the vitreous space of right eyes and DiASP (green) into left eyes. Images were collected with a confocal microscope at P3 through the visible thickness of the optic chiasms at 5 µm intervals. (A) Wild-type optic chiasm showing representative decussation. (B) Brn3b^–/– optic chiasm showing highly abnormal crossing patterns. Optic nerves were thinner than those from wild-type and many axons were observed sprouting from the optic nerve and projecting to the ventral hypothalamus. (C) Brn3b/Brn3c double-mutant optic chiasm showing partially restored decussation. (D-F) Axons from the left eye of those shown in A-C to visualize the small portion of ipsilaterally projecting axons. Note the abnormally abundant ipsilateral axons in E and the absence of misrouted and ipsilateral axons in F.