Expressed in the developing eye from stage 23. Localized to the prospective retinal layer and a layer of cells lateral to the ventricular zone. At stage 29, expression extends to the branchial arches and the brain. At stage 33/34, expressed in the vagal ganglion. At stage 36, expression in the retina decreases. Not expressed in the eye lens. Expressed both maternally and zygotically. Present in all embryonic stages including early cleavage stages, with levels decreasing slightly during gastrulation and neurulation (stages 10-20). Levels then increase at stage 30 and expression persists until stage 45.