Experimental study was performed on hematogenous metastasis by intravascular grafting of material, resulting from serial subcutaneous and intracerebral transplantations of tumor, which was produced after intracerebral implantation of a chemical carcinogenic agent.
1. 20-methylcholanthrene was intracerebrally implanted into 17 C57 B1 mice, and tumor formation was confirmed in 3, which survived more than 108 days. One case was glioma, showing the the histological picture of glioblastoma, and the other 2 were fibrosarcoma.
2. Electron microscopy of the glioma revealed, in glioma cells, virus-like, spherical, double-sheathed particlle, 80-90 mμ in diameter.
3. Tumor cell suspensions from 1 case of sarcoma and 1 case of glioma were respectively infused into the carotid artery of animals. Formation of intracranial metastatic focus was observed in 19 of 40 cases ot sarcoma (47.5%) and in 4 of 17 cases of glioma (23.5%).
4. In 18 of the 19 cases of metastatic sarcoma, the metastatic focus was formed in the cerebral parenchyma, where-as in cases of metastatic glioma, the focus was mainly found in the meninx and choroid plexus of the ventricle. There was thus difference in the site of metastasis.
5. Observation of the early picture of the metastatic focus disclosed that tumor cells were proliferated in contact with the basement membrane of the small vessel or in the adventitia of the venule. After being attached to vascular wall, tumor cells are considered to escape from the vessel to continue proliferation.
6. When sarcoma was intravascularly transplanted, an extensive infarction focus was formed with the center in the cerebral hemisphere on the infusion side. It is highly probable that when sarcoma cells pass through the brain, they produce embolus in the cerebral trunk artery and infarction lesion in the ceredral parenchyma, and that in addition to the biological properties inherent to sarcoma cells, endothelial disorder and hyperpermeability of the parenchyma vessel accelerate the implantation of sarcma cells in the parenchyma as well as their extravasation.
7. When glioma cells were implanted after preliminary mechanical damage to the cerebral parenchyma, metastasis was found in the meninges and choroid plexus in 8 of 19 cases. Two of these 8 showed metastatic focus also in the parenchyma, and one demonstrated proliferation of tumor cells in the damaged site. It seemed consequently that environmental factor on the side of the organ may also play an important part in the establishment of hematogenous metastasis.
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