Increased angiogenesis due to C3-deficiency is dependent on macrophages. WT or C3^−/− mice were subjected to the ROP model and animals were injected with control liposomes or clodronate liposomes to deplete macrophages. Retinal neovascularization was quantified on day p17. Retinal neovascularization is presented as the number of epiretinal neovascular nuclei per section. Data are mean ± SEM (n = 12-17 pups per group) and are shown as percentage of control. Number of epiretinal nuclei in WT mice treated with control liposomes represents the 100% control. *P < .05; ns, not significant.