“…Notably, at E13.5, -gal activity was localized to cells in the neuroblast layer close to the RPE, which correspond to the region where presumptive photoreceptors are localized, raising the possibility that Wnt signaling plays a role in photoreceptor development. Wnt-3, -5a, and -7b have been shown to play a role in precursor cell proliferation in several tissues including the limb, hair follicle, lung, and caudal regions of the embryo (McMahon et al, 1992;Gofflot et al, 1998;Millar et al, 1999;Yamaguchi et al, 1999;Reddy et al, 2001;Shu et al, 2002). Wnt-5b is expressed in the developing gut (Lickert et al, 2001); however, the function of Fig.…”