Medaka mutants with defective retinotectal projection. Fluorescent carbocyanine 1,1′-dioctadecyl-1 to 3,3,3′,3′-tetramethylindocarbocyanine perchlorate (DiI) was injected into a part of the left eye (Le) to visualize the retinal axons at day 9 (stage 40). Larvae were counterstained with DAPI to outline the optic tectum (Tc). In wild-type larvae, retinal axons originating from an eye project into the contralateral tectum (A, C). In dek mutant larvae, a subset of retinal axons deviates from the normal path after exiting the eyes and follows the ipsilateral route (B, arrow). In ogi mutant larvae, a subset of retinal axons misroute in random directions (D, arrows). (A, B) Semi-frontal view. (C, D) Semi-lateral view. Dotted circles show the location of the left eye, which is removed after axons are labeled. Dotted line shows the midline (m).