Changes in T-cell development in TgB are induced by IL-7 overexpression in the thymus. In bone marrow chimera experiments, adult B6 lethally irradiated mice were injected intravenously with a 1:1 ratio of Tg⁺ (CD45.2) or Tg^– (CD45.2) bone marrow cells to congenic Ly5.2 (CD45.1) cells. Thymocytes from individual lobes were analyzed as indicated 7 to 12 weeks after the procedure. Dot plots of CD4/CD8 profiles on (A) total thymocytes or (B) on cells derived from normal coinjected CD45.1 donors. The percentage of events corresponding to each quadrant is shown. (C) Bar graph showing the percentage of the normal coinjected CD45.1 cells in the thymus of mixed bone marrow chimera recipients. (D) Bar graph showing the induction of the transgenic phenotype on the normal coinjected CD45.1 cells in Tg⁺ recipients in a representative experiment. BMT indicates bone marrow transplantation.