PolyP-induced changes in fibrin ultrastructure. Fibrin clots were prepared by incubating fibrinogen (3μM) with thrombin (0.25 U/mL) and CaCl₂ (5mM) in the absence (A,C,E) and the presence (B,D,F) of polyP₆₅ (325μM)_. Fibrin clots analyzed by laser scanning confocal microscopy (A-B) and were analyzed by scanning electron micrographs (C-F). A total of 10 different areas were visualized in 3 replicate clots, and representative pictures are shown. The high-magnification images (E-F) show details of a tightly knotted fibrin region in the presence of polyP (F).