Effect of a single intravenous injection of rmMGDF on the frequency of (A) 2N-4N megakaryocytes and (B) 8N-128N polyploid megakaryocytes. The frequency of 2N/4N cells was significantly increased from days 2 to 4 in mice treated with 25 μg/kg of MGDF and from days 2 to 5 in mice treated with 250 μg/kg ofMGDF (A). The frequency of 8N-128N cells was significantly increased from days 3 to 5 in mice treated with 25 μg/kg MGDF and from days 2 to 14 in mice treated with 250 μg/kg MGDF (B). At 12 hours, the frequency of 8N-128N cells was significantly decreased with the 250-μg/kg dose of MGDF (B). Each data point represents the mean ± SEM of megakaryocyte frequency; for the 25-μg/kg dose, n = 4-10 mice per MGDF group and n = 13 for controls and for the 250-μg/kg dose, n = 5-9 mice per MGDF group and n = 20 for controls. Data from control mice were pooled to represent the day 0 data point.