title: Analysis of the cell cycle of late erythroid progenitor cells by sedimentation at unit gravity.
abstract: Approximately 70% of the late erythroid progenitor cells (E-CFU) which are present in normal bone marrow are killed by exposure to high specific activity tritiated thymidine (3H-TdR) in vitro or to hydroxyurea in vivo, indicating that a high proportion of these cells synthesize DNA. Their cell cycle was further analyzed by sedimentation at unit gravity. The modal sedimentation rate of 7.4 mm/h appeared to correspond to the fraction that is killed by 3H-TdR. Cells sedimenting at 6.0 and 9.5 mm/h were not susceptible to kill by 3H-TdR and correspond to cells in, respectively, G1 and G2/M. Based on a buoyant density of 1.077 g/cm3, the modal diameter of cells in G1 was calculated to be 8.3 micron, in S 9.2 micron and in G2/M 10.5 micron. The E-CFU population appeared to be composed of about 18% G1 cells, about 70% S phase cells and about 12% G2/M cells. The surviving fraction of E-CFU 2 h after intraperitoneal administration of 1 g/kg hydroxyurea was identified as being mainly a synchronous population in early S phase. The data are best explained by a short duration of G1 and G2/M phases.
mesh_terms: D000818:Animals; D001854:Bone Marrow Cells; D002453:Cell Cycle; D002469:Cell Separation; D002478:Cells, Cultured; D002499:Centrifugation, Density Gradient / Q000379:methods; D005260:Female; D006412:Hematopoietic Stem Cells / Q000166:cytology* / Q000187:drug effects; D006918:Hydroxyurea / Q000494:pharmacology; D007399:Interphase; D051379:Mice; D008815:Mice, Inbred Strains; D014316:Tritium
chemical_list: D014316:Tritium; D006918:Hydroxyurea