Fig. (5) Photomicrograph of the control tumor at 7 days shows a markedly cellular appearance and the compactly arranged dense nuclei (A: H&E, X 960) and reveals the preserved tumor cells (arrows) in hemorrhagic areas (B: H&E, X 960). The infected tumor at the same interval shows necrosis and dark areas (arrows) (C: H&E, X 375), and in the dark areas, severe degeneration of the pyknotic nuclei is observed under higher magnification (D: H&E, X 960). Ultrastructure of the control tumor at 7 days show the large nuclei with a small amount of cytoplasm with preserved subcellular organelles (E: X 16,000). The infected tumor at the same interval reveals severe degeneration with a marked loss of the ribosomes (arrow), alterations of the subcellular organelles and accumulation of vacuoles (arrowheads) (F: X 61,000).