Transcription factors essential for normal hematopoietic development as defined by gene targeting studies in murine embryonic stem cells

The primitive hematopoietic stem cell gives rise to nucleated erythroid cells at the yolk sac stage of development. Subsequently, multilineage hematopoiesis is thought to be derived from the the definitive hematopoietic stem cell. The origins and relationships of the primitive and definitive hematopoietic stem cells remain controversial. Experimental evidence suggests that a common precursor to the primitive and definitive hematopoietic stem cell may exist (blast cell colony-forming cell). The precise hematopoietic pathways remain to be defined.