CD45.2⁺ B6 mice were transplanted with a single thymus lobe from 1-d-old CD45.1⁺ B6 mice. (A and B). Frequencies (histograms) and CD4/CD8β phenotypes (dot plots) of CD45.1⁺ donor thymocytes persisting in the thymus graft. (A). Hosts were WT, Rag2, Rag2γ_c, or Rag2 IL-7R–deficient, studied 1 mo after transplantation. (B) Hosts were Rag2γ_c-deficient, studied at different time points after transplantation. Similar results were obtained when hosts were Rag2 IL-7R–deficient. Results are from 1 experiment representative of 8 WT, 12 RagIL-7R–deficient, and 45 Rag2γ_c-deficient grafted mice, studied from 2 wk to 7 mo after grafting. (C) Stem cell precursors in the BM of host Rag2γ_c⁻ transplanted mice, 3 mo after grafting. Results show Ter119⁻GR1⁻Mac1⁻ cells of graft (CD45.1⁺) and the host (CD45.2⁺), and are representative of 5 individual mice studied in two experiments. (D) Repopulation of the transplanted thymi in different host mice. The CD44/CD25 phenotypes of CD45.2⁺ TN thymocytes derived from the host BM, 1 mo after grafting. They are representative of three experiments.