Quantification of CD31+ structures within embryoid bodies. (a) Percentage of EBs containing CD31+ cords only, sheets only, both cords and sheets, or neither structure, as defined in Methods. (b) Relative CD31+ area on EB sections, measured in pixels and shown as a ratio of DAPI+ pixel number. Statistical significance was determined by one-way ANOVA followed by a Bonferroni post-test. (c) Relative CD31+ area on EBs sections; EBs grown +/- TGF-β. Statistical significance was determined by two-tailed, unpaired, t-tests. Bars are means ± S.E.M. (Emp, empty lentiviral construct; Scr1, scrambled siRNA sequence; KD1-3, knock-down siRNA sequences; n = 16-36 for controls, n = 20-29 for knock-downs; * p < 0.05, ** p < 0.01, † p < 0.005, †† p < 0.001). The data shows results from one experiment, which was carried out twice with similar results.