PATHOLOGICAL STUDIES ON THE ONCOGENESIS OF ADENOVIRUS TYPE 12 IN HAMSTERS

Abstract

The sequence of tumor development induced in hamsters by adenovirus type 12 was studied in the subcutaneous tissue by means of light- and electron microscopy and fluorescent antibody technique. The results showed that: the inoculated virus penetrated into mesenchymal cells within 2 hr. after inoculation, the similar cells produced tumor (T) antigen within 24 hr, and a few of these cells seemed to change into malignant cells about 3 weeks later. The histology of well developed tumors revealed a sarcomatous pattern in most areas and an epithelioid in part. Argyrophile and collagen fibers were abundant in earlytumors, while In well developed tumors they were not so prominent. Electron-microscopically fibrogenetic and phagocytic findings were observed in the tumor cells. Neither desmosome nor basement membrane was recognized in the tumor cells, though an increase of density was rarely found in the intercellular space where the cytoplasmic fingers were in contact with the membrane of other cells. The tumors found in subserosa by intraperitoneal and intrapleural injections and those developed from parenchyma of the liver and lymph nodes by intravenous inoculation, were histologically identical to the subcutaneous one. The tumors were also found in the lumbar spinal cord after intracranial inoculation, which was histologi-cally similar to the subcutaneous ones with no evidence of neuroglial fibers. Under these circumstances, it seems justifiable to conclude that adenovirus 12 tumors are originated from "primitive, multipoten-tial mesenchymal cells".