Fibrin sealant and TachoSil. (A-C) Fibrin sealant. Fibrin glue (macroscopic image in A) has a solid, bright eosinophilic and slightly lamellated appearance on H&E with rare, entrapped air bubbles (B, C). (D-F) TachoSil. TachoSil is a mixture of human fibrinogen and human thrombin on an equine collagen sponge. The fibrinogen-thrombin coating forms the dense surface (D, top surface with yellow hue on the macroscopic image), and a porous white side (D, porous bottom). This appearance is readily identifiable microscopically (E, F). As TachoSil is compressed, the porous side appears as stacked lamellae and the dense coating becomes more compact (F). The compact coating retains multiple entrapped air bubbles (F). Scale bar = 100 µm.