Gallery of platelet granules with different substructure. (A) Chemical fixed platelets. Panel of x-y slices, z-axis orientation, and 3D reconstructions of α-granule profile showing the eccentric localization of the 12-nm-wide tubules representing polymeric VWF assemblies. (Ai) x-y slice of a single VWF tubule (arrow). (Ai-iv) Multiple eccentrically localized VWF tubules (red dots in iii). Arrow indicates the same tubule in z-axis orientation. An animation is included as supplemental Video 4. (B) Panel of VWF tubules from HPF-FS platelets. (Bi-ii) The same polymeric VWF tubule in 2 different orientations. (Biii) A kinked VWF tubule (arrow). The VWF tubule in panel Biv (highlighted in Bv) reveals a helical-like substructure. (Ci-iv) Tomographic reconstruction of immunogold-labeled α-granule, double-labeled with anti–P-selectin (10-nm gold, indicated by yellow dot), and CD63 (15-nm gold, indicated by red dots). The 40- to 80-nm free luminal vesicles are distinct from the tubules shown in panels A and B. (Ai) Bars represent 100 nm. (Aii-iii′, Bi-iv) Bars represent 50 nm. (Bv) Bars represent 25 nm. (C) Bar represents 50 nm.