Loss of At3 prevents endothelial injury induced venous occlusion. The endothelium was targeted and injured at 3 dpf, and the time to occlusion measured in seconds with a maximum of 120. All data shown are from Δ90 mutants. (A) Time to occlusion of larvae derived from at3^+/− incrosses at 3 dpf (at3^−/−, n = 16). Results were similar for at3^Δ22 mutants. (B) Time to occlusion of larvae (3 dpf) derived from at3^+/− incross progeny injected at the 1-cell stage with the zebrafish at3 cDNA transgene (at3^−/−, n = 36) is significantly different from homozygotes in panel A, P < .0001. (C) Time to occlusion of larvae (3 dpf) derived from at3^+/− × at3^−/− progeny injected at the 1-cell stage with the human at3 cDNA transgene (at3^−/−, n = 61) is significantly different from homozygotes in panel A, P < .0001. Circles represent individual larvae. Data are from at least 3 independent experiments. Statistical significance was determined by the Mann-Whitney U test. Horizontal bars represent the median time to occlusion.