Quantification of Ki67+ cells within embryoid bodies. The effect of Egfl7 knock-down on in vitro proliferation was quantified in day 7 and day 14 EBs using an antibody against Ki67. Relative Ki67+ area was measured in pixels and shown as a ratio of DAPI+ pixel number. (a) Whole EB sections were compared between control and knock-down clones at each time point (n = 10-16 for controls, n = 9-23 for knock-downs). (b) Relative Ki67+ area of whole EBs, and CD31+ sheet areas, in knock-down EB clones. Statistical significance was determined by two-tailed, unpaired, t-tests. Bars are means ± S.E.M (Emp, empty lentiviral construct; Scr1, Scr2, scrambled siRNA sequences; KD1-3, knock-down siRNA sequences; n = 9-23 for whole EBs, n = 1-47 for CD31+ sheets; * p < 0.05, ** p < 0.01, † p < 0.005, †† p < 0.001).