Thymic architecture and thymocyte cellularity are largely unaltered in Ccr4^−/− mice. (A) Immunostaining of CD4 (purple), CD8 (green), and mTEC-specific keratin 5 (K5; red) in thymic cryosections from Ccr4^+/+ versus Ccr4^−/− mice. Bar, 100 µm. Representative of two mice in each group. (B) Representative immunostaining of K5 (red) and keratin 8 (K8; green), marking medullary and cortical epithelium, respectively, in Ccr4^+/+ and Ccr4^−/− thymic cryosections. Bar, 1 mm. (C) The ratio of cortical to medullary areas in Ccr4^+/+, Ccr4^−/−, and Ccr7^−/− thymic cryosections was calculated from images as in B. Mean + SEM are compiled from analysis of 5 Ccr4^+/+ mice, 6 Ccr4^−/− mice, and 3 Ccr7^−/− mice. (D) Representative flow cytometric analysis of CD4 versus CD8 profiles from Ccr4^+/+ and Ccr4^−/− thymi. (E) The absolute cell numbers (above) and percentages (below) of thymocyte subsets in Ccr4^+/+ and Ccr4^−/− thymi were calculated from flow cytometric analysis, as in D. Means + SEM compiled from six independent experiments with a total of 11 Ccr4^+/+ and 16 Ccr4^−/− mice. *, P < 0.05 (unpaired Student’s t test).