Reduced cTEC to thymocyte ratio in CCX-CKR^−/− thymi. (A) Representative dot plots of MHC II and Ly51 expression on CD45⁻EpCAM⁺ cells to delineate TEC populations: cTEC^lo, MHC II^loLy51⁺; cTEC^hi, MHC II^hiLy51⁺; mTEC^lo, MHC II^loLy51⁻; and mTEC^hi, MHC II^hiLy51⁻. Numbers adjacent to gates indicate percent positive in each. (B) Quantitation of TEC proportions (left) and numbers (right). Data pooled from 2 independent experiments ± SD: WT, n = 12; and CCX-CKR^−/− = 12. Two-tailed unpaired t test (% mTEC MHC II^hi and number of mTEC MHC II^lo): *P = .0249, ***P = .0004. Two-tailed unpaired t test with Welch correction (number mTEC MHC II^hi): **P = .0048. (C) Quantitation of the number of CD45⁺ cells per cTEC and mTEC ± SD from the data in panel B. Two-tailed unpaired t test: *P = .0166. (D) Quantitation of the number of thymocytes per Aire⁺ TEC (right). Data from a single experiment ± SD; n = 5. Two-tailed unpaired t test: ***P = .0007.