Intravital morphological study for growth of hematogenous lung metastasis of SATO lung cancer in the rat

Intravital microscopic observation for pulmonary metastasis was performed in living rat. Intravenously infused cancer cells arrested in pulmonary microvessels in following three styles. Cancer cells of the Ist style thrust into the endarterioles, the 2nd style were caught on aretriolar wall, and the 3rd style arrested in the arteriole like a balloon in the sky. The Ist and 2nd styles, which occupied 97% of arrest cells, might be dead, because they must have strong mechanical stress from vessel wail and blood stream. Arrest cancer cells begun to grow in 3 days, increased their size enormously in 4 to 5 days, and reached to mature tumors in 6 to 7 days after cancer cells injection. Vessel numbers around arrest cells were 2000/mm2. Tumor vessel numbers were 4000/mm2 in 3days, 5000/mm2 in 4-5days and 4500/mm2 in 6-7 days after cancer cells injection. Our vital observation system was very useful for studying the details of lung cancer.