Combined pretreatment with KGF + PFT-β additively restores all TEC subsets by 4 weeks after congenic BMT. Lethally irradiated B6 recipients of congenic (B6 Ly5.1⁺) BM were left untreated (BMT Control) or pretreated with KGF, PFT-β, or KGF + PFT-β and analyzed for absolute numbers of total (A) TECs (CD45⁻EpCAM⁺MHC-II⁺) and (B) thymocytes (SSC^lowCD45⁺EpCAM⁻MHC-II⁻) at 2 weeks after BMT. (C-G) Immunofluorescence staining of thymic sections at 2 weeks after BMT for the cytokeratin-5, K5 (red) and Ly51 (green) identified mature cortical TECs (Ly51⁺K5⁻) and medullary TECs (Ly51⁻K5⁺). These methods were used to assess recovery of distinct cortical and medullary TEC populations. Images were acquired on an Olympus FV500 confocal microscope with the use of a 10×/0.40 objective lens with associated Olympus Software. (H) Total thymocytes, (I) total TECs, (J) cTECs (CD45⁻ EpCAM⁺ MHC-II⁺Ly51⁺), (K) mTECs (CD45⁻EpCAM⁺MHC-II⁺Ly51⁻), and (L) AIRE⁺ mTEC^hi (CD45⁻EpCAM⁺UEA-1^highMHC-II^highLy51⁻ AIRE⁺) were quantified in thymi from BM transplant recipients and non-BM transplant controls (nonBMT Control) at 4 weeks after BMT. For FACS analysis, data shown are the mean numbers of cells ± SEMs and are representative of 3 experiments of 4 mice per group; *P < .05. For immunofluorescence microscopy, data are representative of 2 experiments, each with 3 mice per group.