passages.id: split_8_test_763_passage
passages.type: progene_text
passages.text: To examine the expression of the Flk-2 / Flt-3 receptor on megakaryocyte progenitors ( CFU-Meg ) , Flk-2 / Flt-3 positive and negative CD34 ( + ) populations were separated from human bone marrow and cultured in a plasma clot culture system .