Thrombus formation on collagen type III surface under high shear. (A) The mean surface coverage after 2.5 minutes' perfusion tended to be higher with “aa” blood compared with “bb.” Data are expressed as the mean ± SEM and tested by Mann-Whitney U test. (B-C) Typical examples of coverslips representing the mean percentage of surface coverage are depicted for “aa” blood (B) and “bb” blood (C).