Transmission electron microscopy of rotary shadowed PF4-heparin complexes. Fields demonstrating the appearance of PF4-heparin complexes at the optimal PF4-heparin ratio. Triangles (▸) indicate representative ULCs; arrows point to representative SCs. The coating of metal from the shadowing technique makes the extended structure of the IgG appear artificially larger in comparison to that of compact structure of the PF4-heparin complexes. Magnification bar = 50 nm.