Progressive loss of TECs in Mcl1^ΔFoxn1mice. (A) TEC (CD45⁻MHC II⁺EpCAM⁺) numbers from control and Mcl1^ΔFoxn1 mice at different time points. Representative flow cytometry plots (B) and graphs showing proportions (C) and absolute numbers (D) of cTECs (Ly51⁺UEA-1⁻) and CD80⁺ and CD80⁻ mTECs or total mTECs (Ly51⁻UEA-1⁺). Representative flow cytometry plots (E) and graphs showing absolute numbers (F) of CD80⁺ mTECs expressing AIRE in day 9 Mcl1^ΔFoxn1 mice. Representative histograms (blue and red histograms show controls and Mcl1^ΔFoxn1 mice, respectively) (G) and graphs showing proportions of proliferating Ki67⁺ TECs (H). Data are representative of at least 2 independent experiments (n ≥ 3/group) (except TEC subset data for day 9). Graph bars indicate mean ± SEM and groups were compared with a Student t test (2 sided, unpaired). *P < .05; **P < .01; ***P < .001; ****P < .0001. The control group combines various combinations of genotypes (Foxn1^Cre/+Mcl1^+/+, Foxn1^+/+Mcl1^lox/+, Foxn1^+/+Mcl1^lox/lox, Foxn1^Cre/+Mcl1^lox/+) that showed no differences from each other in separate experiments. Immunofluorescence images of thymic sections from day 9 and 2-month-old control and Mcl1^ΔFoxn1 mice stained with anti-K8, anti-K5, and UEA-1 (I); anti-DEC205 and anti-PanK (J); anti-PanK and AIRE (K); and ER-TR7 and anti-PanK (L). Scale bars represent 100 µm (I, J, L) and 50 µm (K). PanK, pan-keratin.