FGF7 and FGF10 arrest of T-cell development. E15 FTOC was cultured for 7 days in the presence or absence of FGF7 or FGF10. (A) Representative FACS dot plots of CD44/CD25 (upper panels) and CD4/CD8 (lower panels) expression by thymocytes from untreated (left panels) and FGF7 (166 ng/mL)–treated (right panels) FTOC. R6, R7, and R8 denote DN1, DN2, and DN3 subpopulations, respectively. (B) Bars represent the relative change of total DN, DN1, and DN3 subpopulations in these cultures in a total of 6 experiments. Increases are significant (^*) with P values denoting greater than 99.9% confidence. (C) Bars represent the relative change in total cell number per lobe in these cultures in a total of 4 experiments with each factor. Decreases with FGF7 and FGF10 treatment are significant (^*) with greater than 99.9% confidence. Error bars indicate mean ± SD.