Morphologic examination of syncytia in HHV-7–infected SupT1 cultures (8 day pi) by light (A) and electron (B through E) microscopy. (A) Field with three syncytia and various single cells. (B) Multinucleated syncytium with an intact morphology. (C) Particular of a necrotic syncytium with vacuolized cytoplasm and initial discontinuation of the plasma membrane. Also note the lack of nuclear chromatin condensation. In (B) and (C), virions appear as dark points (asterisks). (D) Ringed nucleocapsids with an electron-dense core in the cytoplasm of a necrotic syncytium. (E) Particular of a syncytium in advanced stage of necrosis (bottom left), releasing mature virions (asterisks) in proximity of an intact cell (top right). N, nucleus; cy, cytoplasm; v, vacuole; pm, plasma membrane. Original magnifications: (A) ×400; (B and C) ×6,000; (D) ×36,000; and (E) ×7,000.