(A) The effect of administration for 5 days of different doses of M-CSF on the platelet counts of SW mice. M-CSF was administered to SW mice at the indicated total daily dosages, given in two IP injections, 8 hours apart, for 5 days. On days 1 to 5, platelet counts were obtained immediately before the morning M-CSF injection. The mean platelet count ± 1 SE is shown. The number of determinations at each time point was at least 3, and usually ranged from 5 to 28 (mean, 13). The symbols indicate significant differences between the values (P < .05) (★, 2 mg/kg/d v 4 mg/kg/d; ‡, 2 mg/kg/d v 8 mg/kg/d; #, 4 mg/kg/d v 8 mg/kg/d). (B) The effect of administration for 11 days of different doses of M-CSF on the platelet counts of SW mice. M-CSF was administered to SW mice at the indicated dosages, given in two daily IP injections, 8 hours apart, for 11 days. Platelet counts were obtained immediately before the morning M-CSF injection. The mean platelet count ± 1 SE is shown. The number of determinations ranged from 5 to 21 at each time point (mean, 11). The symbols indicate significant differences between the values (P < .05) (★, 2 mg/kg/d v 4 mg/kg/d; ‡, 2 mg/kg/d v 8 mg/kg/d; #, 4 mg/kg/d v 8 mg/kg/d).