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In vitro development of CFU‐E and BFU‐E in cultures of embryonic and post‐embryonic chicken hematopoietic cells

A culture method is proposed for the in vitro development of chicken erythrocytic progenitors. When grown with avian erythropoietin, Colony Forming Unit Erythrocytic (CFU‐E) and Burst Forming Unit‐Erythrocytic (BFU‐E) give rise respectively to erythrocytic colonies and bursts within 3 and 6 days. BFU‐E development is greatly enhanced by pokeweed‐mitogen‐spleen‐cell‐conditioned medium and requires higher erythropoietin concentrations than for CFU‐E. An antigen specific to immature red cells can be detected on CFU‐E but not on BFU‐E, showing that both progenitors represent distinct entities. BFU‐E and CFU‐E are found in embryonic marrow and yolk sac. In the young blastoderm BFU‐E becomes detectable at the primitive streak stage.