EM images of inferior vena cava thrombi in AA vs AS mice. (A) Typical tightly packed polyhedrocytes in thrombi from AA mice as seen on scanning EM images. (B) In contrast, multiple sickled RBCs with extruding membrane spicules are visible in the core of a thrombus from an AS mouse alongside some nonsickled cells. (C-D) Transmission EM images illustrating tightly packed RBCs (“polyhedrocytes”) in a thrombus from an AA mouse, compared with the loose packing in a clot from an AS mouse. EM, electron microscopy.