Analysis of the proliferative capacity of individual clones. The proliferative potential of each unique or common clone detected in femur, BM, and spleen from Figure 3D was estimated by using densitometry analysis of Southern blots. The approximate cellularity of the day 1 (n = 137) and day 4 (n = 43) marked clones was calculated from the intensity of each band, divided by the combined intensities of all bands in a single lane loaded with DNA from the hematopoietic tissue, and multiplied by the number of GFP⁺ cells collected from this tissue. (A) The proportion of clones corresponding to each clonal size is indicated. (B) Each bar represents the average size (± SE) of the clones from the mice given transplants of day-1 or day-4 cells from 7 experiments.