Pathogenesis of oncogenic simian adenoviruses. IV. The histopathology and ultrastructure of intraperitoneal neoplasms induced by SV20

The histopathology and ultrastructure of SV20‐induced intraperitoneal (IP) neoplasms is described and compared to neoplasms induced by this virus administered by the intracranial and subcutaneous routes. SV20‐induced IP neoplasms are relatively undifferentiated and contain two types of tumor giant cells. Dilated rough endoplasmic reticulum was increased, but annulate lamellae were rarely observed in IP neoplasms. Virus‐like particles within the cytoplasm and nuclei of neoplastic cells resembled the original inoculated SV20 virus. Virus particles associated with cisternae of endoplasmic reticulum, nuclear projections, and unusual cytoplasmic bodies with many smaller dense structures were observed. These latter dense structures were attached to the inner and outer surface of cytoplasmic bodies and resembled the nucleoid of virus particles.