Transmission electron microscopic observation of CFU-mix culture in normal adults and leukemia patients.

By use of transmission electron microscope we demonstrated that the limiting dilution assay is an important method for investigating differentiation of hemopoietic cells in vitro. If various growth factors were added into this culture system, the stem cells of normal adults could differentiate into erythrocyte, granulocyte, megakaryocyte and macrophage, while leukemic progenitor cells could not. The colony forming cell in leukemia still had the nature of leukemic cell.