Initial chimerism in recipients of allogeneic IUHCT. Initial PB hematopoietic chimerism was measured at 3 weeks of age in B6Ly5.2 recipients of prenatal Balb/c donor fetal liver cell transplants. Recipients are grouped according to cell dose at transplantation (2 × 10⁴-2 × 10⁶ cells/fetus). (A) The engraftment prevalence (> 0.3%) at the initial PB analysis for each recipient group. (B) Chimerism level at initial PB analysis for each recipient group. Data points represent the mean value plus or minus standard error of the mean (SEM).