Minimal percentages of initial CD34⁺ fetal liver (FL, □) and cord blood cells (CB, ▪) with the ability to divide from 0 to 6 times in short-term cultures containing 5 growth factors (same experiments as shown in Fig 2). A similar calculation could not be made for cells that underwent more than 6 divisions; however, by subtraction this can be estimated as 78% ± 3% for fetal liver cells and 45% ± 5% for cord blood cells. Values shown are the mean ± SEM from 5 (FL) and 6 (CB) experiments.