Effect of the murine stromal cells MS-5 on the output of CFC and LTC-IC. In 6 to 10 experiments, 10,000 CD34⁺CD38^low cells were grown in the presence of 10% FCS with low GF and in the presence (▪) or absence (░) of MS-5 cells. After 10 days, aliquots of cells were assessed in colony-assays and 5-week LTC-IC assays and the absolute numbers of CFC and LTC-IC derived from 10,000 input cells were calculated. Histograms represent the mean ± SEM of the absolute number of CFC and LTC-IC obtained from 6 to 10 independent experiments.