Figure 1

Dkk3 protein is expressed in the retina during Müller glial cell differentiation. Dkk3 immunoreactivity is present diffusely in the developing retina at P5 and at P8 it is localized to the outer plexiform layer (OPL), the site of synaptic processes between photoreceptors and interneurons, and the ganglion cell layer (GCL), where it remains at P10 and P12. During the later stages of retinal differentiation Dkk3 becomes predominantly localized to the inner nuclear layer (INL) and at the inner segment region (IS, arrow), consistent with localization to Müller glia cell bodies and end-feet. Expression in the OPL and GCL remains high at these ages. By P20, Dkk3 appears localized along radial fibers, representing Müller glia processes, extending across the retina. These fibers are particularly visible in the outer nuclear layer (ONL). IPL, inner plexiform layer.