These graphs depict the triphasic kinetic profiles for the frequency of donor cells circulating within the recipient fetal peripheral blood (cord blood) or lodged within the fetal liver at various time points (1.5 to 96 hours) after in utero transplantation. The nearly identical profiles for both the congenic (A) and the fully allogeneic (B) strain combinations are shown. The donor cell frequency is calculated as the percentage of cells expressing the donor CD45.1 isoform among all CD45⁺ cells within the host cord blood or fetal liver.