title: Characteristics of rat megakaryocyte colonies and their progenitors in agar culture.
abstract: The characteristics of megakaryocyte colonies that develop from megakaryocyte progenitors of rat bone marrow stimulated by rat spleen-conditioned medium (SCM) in agar culture were investigated. Colony frequency was optimal on day 7 and increased relative to both the number of cells plated and the concentration of SCM used. Plating efficiencies averaged 72 +/- 16 megakaryocyte colonies/10(5) cells with 0.1 ml SCM/culture. Colonies were categorized as small cell and big cell. Small-cell colonies had a greater proliferative potential, with a mean of 25 cells/colony. Big-cell colonies averaged 15 cells/colony. The ratio of big-cell to small-cell colonies was 0.69 +/- 0.29. Granulocyte-macrophage colonies, which were also stimulated by SCM, accounted for 70% +/- 15% of the total colonies in the cultures. Cytocidal experiments with tritiated thymidine reduced megakaryocyte colony formation by 45% and granulocyte-macrophage colony formation by 21%. The properties of rat, mouse, and human megakaryocyte progenitors as assayed in vitro are compared.
mesh_terms: D000362:Agar; D000818:Animals; D001854:Bone Marrow Cells; D002478:Cells, Cultured; D003470:Culture Media; D046508:Culture Techniques / Q000379:methods; D004261:DNA Replication; D006412:Hematopoietic Stem Cells / Q000166:cytology*; D007700:Kinetics; D008533:Megakaryocytes / Q000166:cytology* / Q000378:metabolism; D051381:Rats; D011919:Rats, Inbred Strains; D013936:Thymidine / Q000378:metabolism; D014316:Tritium
chemical_list: D003470:Culture Media; D014316:Tritium; D000362:Agar; D013936:Thymidine