MBEC transplantation is associated with accelerated recovery of mature blood counts. Peripheral blood was collected every 3 to 4 days following the administration of 700 cGy total body irradiation to C57Bl6 mice. Groups of mice were given intravenous (n = 10, blue line) or intraperitoneal (n = 10, gray line) transplants of MBECs, and hematologic recovery was compared with that of irradiated control mice (n = 10, black line). The mean total WBCs and Plt counts were markedly reduced in all mice through day +14. By day +20, mice that received either intravenous or intraperitoneal MBECs demonstrated increased total WBC counts compared with control mice (A). (B) Mice that received intravenously administered MBECs displayed significantly increased platelet counts at day +17 compared with untreated controls, and mice that received either intravenous or intraperitoneal MBECs had higher platelet counts at day +20. *Significant difference in the levels between the group that received intraperitoneally administered MBECs and control mice; ∧significant difference between the mice that received intravenously administered MBECs versus untreated control animals. Standard errors about the mean are shown as error bars.