Asymmetric Numb segregation in dividing thymocytes. (A) CD4 and CD8 expression in fetal thymocytes of WT mice, analyzed by flow cytometry. Numbers represent percentages of CD85P; DP, CD45P, and DN subpopulations (clockwise from top left). (B) Confocal image of a 15-day fetal frozen WT thymus stained with CD25. (C) Confocal images of mitotic WT fetal thymocytes stained with antibodies against Numb (green), CD25 (red), and treated with TOPRO-3 iodide (blue). The images are representative of at least 3 independent experiments. (D) Percentage of Numb protein contained in each daughter cell at the telophase stage. Quantification of Numb signal was performed as indicated in “Quantification of fluorescent staining in z-stacks of dividing cells.” DC #1 and #2 represent the daughter cells that inherited more and less Numb on each z-stack, respectively. A total of 10 telophases were analyzed. Average standard deviation for DC#1 and DC#2 = 10.31. Horizontal lines represent avarage values.