Mechanics of Blood Clots (image) University of Pennsylvania School of Medicine Share Print E-Mail Caption This is a colorized scanning electron micrograph of a coronary artery thrombus taken from a patient who had a heart attack. Fibrin fibers are brown; platelet aggregates are gray; red blood cells in red; leukocytes are depicted in green. Credit John Weisel, PhD, University of Pennsylvania School of Medicine Usage Restrictions None Share Print E-Mail Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.