Tracking analysis of individual clones. The activity of individual clones over time in mice that underwent primary (1°), secondary (pair 2°a, 2°b), and tertiary (pair 3°a, 3°b) transplantation is shown. All mice that underwent tertiary transplantation received bone marrow from the corresponding secondary mouse 2°b not 2°a. Clone numbers refer to listed clones in Table 1. Dark squares indicate time points where the clone was detectable either by LAM-PCR and sequencing or by clone-specific tracking PCR. n.d. indicates not done.