Platelets are associated with valvular cells. (A) Whole-mount confocal staining (CD41 [green], CD62P [red], and 4′,6-diamidino-2-phenylindole [DAPI; blue]; upper-left and upper-middle panels) for activated platelets and corresponding SEM (valve surface) images of the same area (lower-left and lower-middle panels) in LDLR mice 6 months after HFD. Yellow arrows indicate activated platelets. High-magnification whole-mount staining (upper-right panel) and SEM (lower-right panel) images of aortic valve (from LDLR mice fed with HFD) show activated platelets are physically attached to valvular cells (yellow and green arrows). (B) Representative SEM images of aortic valve leaflets from WT and LDLR mice 6 months after HFD showing fewer activated platelets in WT than LDLR valves, indicated by yellow arrows (smaller platelet aggregates) and blue arrows (larger platelet aggregates). Quantification of the total number of platelet aggregates on the surface of valve leaflets in WT (n = 5) or LDLR (n = 6) mice analyzed after 6 months of HFD. Two-tailed unpaired Student t test was used to compare the 2 groups. Data represented as mean ± SEM throughout.