CFU-C in Agar

Agar culture systems for the clonal growth and differentiation of hemopoietic cells were first described 20 yr ago (1). The progenitor cells that developed into colonies in agar after several days of culture in the presence of a source of hemopoietic growth factor (2,3) were initially called "Colony Forming Units in Culture" (CFU-C). They are found in bone marrow, spleen, blood, fetal liver, and yolk sac. It was subsequently demonstrated that the CFU-C population was heterogeneous and contained progenitors giving rise to granulocyte/macrophage (CFU-GM), granulocyte (CFU-G), and macrophage (CFU-M) colonies. Progenitor cells of other lineages (erythroid and megakaryocytic) have also been similarly demonstrated in hemopoietic organs.