Phase Contrast Morphology of Coagulation Clot Maturation and Fibrinolysis

Summary Morphologic observations of coagulation, clot maturation and fibrinolysis in thin standardized clots were presented using negative and positive phase contrast microscopy. The study described the beginning of fibrin formation in centers away from platelets and platelet clumps but usually associated with platelet fragments. Although the preparations failed to reveal clot retraction, the fibrin strands did show a change in refractive index. Intact clot preparations were demonstrated several weeks after incubation at 37° 0. The observation of greatest significance, in the light of recent studies accentuating the role of platelets in hemostasis, was the lysis of platelets and platelet clumps which had undergone viscous metamorphosis. This action of plasmin on platelets may be of great importance in the prevention of hemostasis in the fibrinolytic syndrome and the destruction of damaged platelets in the normal circulation.