Chimerism development in unperturbed radiation chimeras. (A) The open circles represent the observed chimerism levels (mean ± 1 SD) in primary radiation chimeras. The ⊗ illustrates the D2/B6 ratio in the FL cell transplant. The simulated chimerism of mature model leukocytes is given by an average of 100 simulation runs (solid line) and its corresponding SD (gray shade). The goodness of fit measure, Δ, equals 0.80. The used transition intensities f_α and f_ω (obtained by fitting the model to the data points) are shown in panels B and C, respectively. The shaded areas in panels B and C indicate stem cell numbers consistent with a regenerated stabilized model system.