The purpose of the present experiment was to observe the morphological characteristics and invasiveness of a transplantable cancer NO 27 (U 27) after serial passages about 20 years. The results were as follows: The morphological characteristics of this tumor strain was low-differentiated carcinoma which were demonstrated by light microscopy and transmission electron microscopy. In the cytoplasm the single irregular distribution of the tensile fibrils and some semi-desmosome between adjacent cells were discovered by transmission electron microscopy. Two types of cancer cells were observed on the surface of the cancer nest by scanning electron microcopy:Ⅰ), There were many microvilli on the surface of the first type cancer cells; 2). The surface of the cancer cells of the second type were more flat sometimes with single small blebs. Many cancer cells had been released from cancer cell clump after 3 days of intramuscular implantation. Later they actively invaded into the spaces between muscle fibers in the form of amebae. Some cancer cells stretched out their filopodia directly in contact with target cells. The degenerative and atrophic changes of muscle tissue appeared in the invasive area of cancer cells. Finally these changes were leading to the disappearance of the entire structure of the muscle with the replacement by cancer tissues.

CNE cells were cultured on cover glasses placed in the culture flasks, and were examined under scanning electron microscope 6,24, 48,72, and 96 hours after cultivation. The results were as following: The surface structures of tumor cells changed in different intervals of cultivation. Evenly distributed zeiotic blebs were found on the surface of tumor cell after 24 hours of cultivation and most of these blebs were seen at marginal areas of tumor cells after 2 days of cultivation, and finally disappeared after 3 days of cultivation. In addition to the blebs some microvilli which had increased since the second day of cultivation were seen over the margin of tumor cells. On the third day of cultivation a large number of microvilli were seen distributed over the entire surface of tumor cells. Besides microvilli and zeiotie blebs, lamellipodia and ruffles were also observed after 24 hours, but vanished after 48 hours of cultivation. The filopodia were seen over the whole process of cultivation. They usually divided into 2、3 branches and the expanded ends looked like suckers. All these data indicated that the surface structure of tumor cells were variable in different periods of cultivation.