Figure 4.

Vax1 homozygous mutants show coloboma and dysgenesis of the optic nerve. (a,b) External view of 12.5-dpc eyes. (c,d) Hematoxylin and eosin staining of transverse section of the optic nerve of 16.5-dpc albino embryos. At 12.5 dpc, the optic fissure is closed in the wild-type eye (a) but remains opened in the mutant eye (b, white arrowhead). At 16.5 dpc, in contrast to the wild-type optic nerve (c), a thick epithelium is observed over the mutant optic nerve fibers (d) running over the open optic fissure (white arrowhead). The arrow in d points to the optic recess. Bar, 0.125 mm.