Flow cytometric analysis of thymocyte proliferation in vivo. (A) The populations analyzed by anti-BrdU staining are shown. The arrow indicates the CD8⁺ population analyzed for BrdU incorporation in panel B. (B) Noncompetitive BrdU incorporation in vivo. The dot plots show representative staining with anti-BrdU, gated for the Ly5.2⁺ and CD8⁺ populations. The values indicate the percentage of the Ly5.2⁺/CD8⁺ cells that are BrdU positive. (C) Graphic representation of noncompetitive BrdU incorporation in CD4/CD8 subsets. (▪) TβRII^-/- (n = 4); and (▦) TβRII^+/- controls (n = 4). (D) Graphic representation of a competitive transplantation experiment. (▪)TβRII^-/- (n = 7); and (□) wild-type competitor cells (n = 7). Results are expressed as mean ± SDs.