Frizzled-5 is a 7-TM receptor for Wnt-5a, Wnt-9b, Wnt-10b, Wnt-2b, and Wnt-7a. It is expressed in many embryonic tissues and in the adult retina, colon, and pancreatic islets, some cancer cell lines, human embryonic stem cells, and in some monocyte and lymphocyte populations. Frizzled-5 plays a role in the maintenance of yolk sac and placental vasculature and in the regression of vitreous vasculature during eye development. It mediates the synaptogenic effect of Wnt-7a, contributes to the development of neuronal polarity, and is required for neuronal survival in the thalamus. In macrophages and monocytes, Frizzled-5 signaling induces the production of inflammatory cytokines.