Thrombosis
This illustration shows how in the vascular lumen erythrocytes (red blood cells) are being held on by a fibrin network (yellow fibers), which causes formation of a thrombus. Thrombosis is the closure of a blood vessels due to a clot of blood. On the left and right side, blue tissue cells with a darker nucleus are depicted. Between them, also in blue, vascular endothelial cells (also with a darker nucleus).