Transmission electron microscopy of BCBL-1 cells treated with TPA plus hr-NGF after 48 hours of culture.

(A) Numerous mature HHV-8 virions (arrows) were observed both in cytoplasm and in dilated cisternae of the endoplasmic reticulum (ER). The small pictures in the upper right-hand corner detail HHV-8 virions in the (1) cell cytoplasm and (2,3) dilated cisternae of ER. In some cases, (2) the outer membrane of the viral particles was connected to the ER membrane, suggesting a possible budding into ER. (B) Electron dense material and mature virions inside intracytoplasmic vesicles (arrowheads) were observed just beneath the cell membrane; a detail at higher magnification is inserted in *. (C) Morphologically mature viral particles are seen in the extracellular space of BCBL-1 cells. The bars in (A, B) equal 400 nm; in (C), 300 nm; and in (1, 2, 3), 200 nm.