Effect of hFIX variants on thrombus formation after laser-induced injury of small cremaster vessels in FVIII-KO mice. (A) Results overview. (B) Representative immune fluorescence images showing the progression of thrombus formation by intravital microcopy after laser-induced vessel wall damage over the course of 180 seconds for each treatment group. Platelet deposition and fibrin generation in arterial and venous thrombi were visualized using an anti-CD41 Alexa Fluor 647– (red) and an anti-fibrin Alexa Fluor 555–labeled Ab (green). §Small, slow progressing clots. *P < .001 according to Fisher exact test including Bonferroni adjustment for multiple comparisons.