Ploidy of purified CD34⁺ cells cultured in the presence of MIP-1α, IL-3, IL-6, IL-11, FL, SCF, and MGDF was evaluated by means of flow cytometry bidimensional analysis (n = 10). Although some megakaryocyte progenitors become polyploid in the first 7 days of culture, more distinct polulations of 4N, 8N, 16N, and 32N CD61⁺ cells were evident at the end of the second week of culture.