Fig. 6. Dnmt3b mutations lead to the apoptosis of thymocytes. (A) Representative FACS profiles showing staining patterns of thymocytes in P1 ICF mice and control mice. Cells were stained with anti-CD4-PE and anti-CD8-FITC for upper panels, and Annexin V-FITC (AnV) and propidium iodide (p.i.) for lower panels. Numbers shown in FACS profiles denote the percentage of cells that fall into each quadrant. (B) Absolute numbers of total thymocytes (total), CD4^-CD8^- double-negative cells (DN), CD4⁺CD8⁺ double-positive cells (DP), CD4⁺ single-positive cells (CD4 SP), and CD8⁺ single-positive cells (CD8 SP) in a T/- mouse and a wild-type littermate. (C) TUNEL staining (upper panels) and DAPI staining (lower panels) of sections of thymus and spleen from a T/- mutant mouse and a T/+ littermate control at P1. (D) Fragmentation of DNA extracted from the thymus, spleen, liver, kidney and brain of ICF mutant mice and their littermate controls at P0 or P1. DNA was analyzed by electrophoresis on a 1% agarose gel and stained with ethidium bromide.