Telomere dysfunction induces alterations in the systemic environment, impairing thymopoiesis. (A-D) Neonatal thymi from G3mTerc^−/− or mTerc^+/+ mice were transplanted side-by-side under the left and right kidney capsules of 2- to 3-month-old G3mTerc^−/− or mTerc^+/+ recipient mice (n = 5 per group). The grafted thymi were analyzed 9 months after transplantation. (A) Representative FACS profiles and (B) bar graph showing the percentage of CD4 and CD8 double-positive (DP) thymocytes in grafted thymi of recipient mice of the indicated genotypes. (C) Bar graph showing the weight of grafted thymi in recipient mice of the indicated genotypes. (D) Bar graph showing the percentage of annexin V–positive, CD4 and CD8 DP thymocytes in grafted thymi of recipient mice of the indicated genotypes. (E-G) Bone marrow cells (1.5 × 10⁶) from 12-month-old G3mTerc^−/− or mTerc^+/+ mice were transplanted into lethally irradiated (12 Gy) 2-month-old G3mTerc^−/− or mTerc^+/+ recipient mice (n = 6 mice per group). Thymi were analyzed 8 months after transplantation. (E) Representative FACS profiles and (F) corresponding bar graph showing the percentage of CD4 and CD8 DP cells in the native thymi of mice of the indicated genotypes that received bone marrow transplants. (G) Bar graph showing the weight of the native thymi of mice of the indicated genotypes that received bone marrow transplants. Error bars represent SD in all panels.