Syngeneic BM engraftment. Syngeneic BM engraftment in (A) BALB.K and (B) B10.BR mice. Female recipient mice were given sublethal TBI and injected with syngeneic male BM at a cell dose of 107. Shown are percent donor chimerism in BM and spleen of recipient mice 6 weeks after transplantation, assayed by quantitative PCR for male-specific Sry DNA.