The effect of multiple courses of M-CSF administration on the platelet counts of SW mice. M-CSF, 8 mg/kg/d, was administered to SW mice in two daily IP injections, 8 hours apart. Mice initially received M-CSF for 11 days, were rested for 4 days, and then received M-CSF on days 16 to 24 and 36 to 43. The mean platelet count ± 1 SE is shown, n = 3 to 4.