Retinal glial cells participate in nearly all proliferative retinopathies. Little is known about factors that can stimulate these cells to migrate from the retina and proliferate. We cultured retinal glial cells from immature rats and observed the migratory and proliferative responses to serum (0% to 10%) and two of its components, platelet-derived growth factor (PDGF) (0 to 30 ng/mL) and fibronectin (0 to 20 mg/L). We found that 1% serum causes a fivefold increase in migration of the retinal glia and a 170% increase in proliferation over baseline. Fibronectin caused a threefold increase in migration at 30 mg/L, and PDGF caused a fourfold increase at 20 ng/mL, but only PDGF caused an increase in proliferation (300% at 10 ng/mL).