Studies on the pathogenesis of Simian adenovirus-induced tumors. III. The histopathology and ultrastructure of intracranial neoplasms

Abstract

SUMMARY-In newborn hamsters, the simian adenovirus 20 (SV20), when administered intracerebrally, induces undirferentiated intracranial neoplasms. Histologically, these viral-induced neoplasms are dirfuse, and although most of the tumor cells are mononuclear, occasional multinucleated forms are present. Examination of the ultrastructure of both multinuclear and mononuclear tumor cells revealed virus-like particles resembling in-fectious SV20 multiplying in vitro in LLC-MK2 cells. These virus-like particles were noted in both the cytoplasm and nucleus of the intracranial tumor cells. An interrelationship between stacks of cisternal smooth endo-plasmic reticulum, annulate lamellae, and the nuclear envelope was also observed in the neoplastic cells. Characteristic changes in the cisternae of the smooth endoplasmic reticulum appear to result in the formation of annulate lamellae. This process is similar but not identical to cytoplasmic vesicles "blebbed orf " from the external membrane of the nuclear envelope. Thus this type of viral-induced neoplasm appears to be of interest for th