Morphology of fibrinogen-fibrin layers on carbon as observed by TEM. Fibrinogen was adsorbed on carbon-coated mica at a concentration of 20 μg/mL for 150 minutes (A) and 500μg/mL for 30 minutes (B), treated with thrombin at 2.5 U/mL for 60 minutes, a mixture of PPACK at 10μM and hirudin at 6 U/mL for 20 minutes, and fibrinogen at a concentration of 200 μg/mL for 60 minutes. The layers were contrasted with uranyl acetate, dehydrated with a series of water-ethanol solutions, and dried.