Experimental setup. Individual CD34⁺CD38^- cells were deposited by fluorescent cell sorting into 96-well plates (1 cell/well), and observed at half-daily intervals. Initially deposited cells that performed their initial cell division between culture days 5 and 10 (category II) were considered for further analyses. Shortly after the first cell division, the arising daughter cells were separated by micromanipulation and individually transferred into secondary plates containing irradiated AFT024 cells as a stromal feeder. After 2 weeks of expansion the entire progeny of each individual daughter cell was split into 4 aliquots and transferred in equal amounts (in duplicates) into primitive myeloid (LTC-IC) or primitive lymphoid (NK-IC) readout assays, respectively. After an additional 7 weeks the assays were analyzed as described in “Materials and methods.” Originally deposited cells as well as singularized daughter cells that had both LTC-IC as well as NK-IC capacity were retrospectively considered ML-ICs.²¹