[Scanning electron microscopic observations on gastric cancer]

On the basis of transmission electron microscopy of the gastric cancer, 10 cases with various types of the same tumor were further observed by Hitachii S-450 scanning electron microscope (SEM). The mucosa of the gastric cancer, para-cancer area and the perigastric lymph nodes were taken and fixed with penta-aldehyde and osmic acid, then processed into scanning specimens. By SEM, the para-cancer mucosa was quite similar to the "normal" gastric mucosa. Its free surface looked like strawberry. The gastric papule and fovea could be seen and the border of the cells was distinct. There was an uneven spacial structure similar to mountains and valleys at the border between the mucosa of the cancer and the non-cancer area. The mucosa of gastric adenocarcinoma showed wornout cotton-like erosion and destruction losing the normal tissue structures. The mucous epithelium was arranged disorderly adhered with marked dyskaryotic cancer cells. In the 2 cases of poorly differentiated adenocarcinoma and 1 undifferentiated carcinoma, metastatic cancer cells were found in the marginal sinuses of the perigastric lymph nodes. The scanogram of SEM showed a cluster of metastatic cancer cells neared and were adhering to the target organ. Some of the cells were observed stretching out their filament pseudopodia and invading the target organ. It implies a subsequent distant metastasis. Further study on the stereostructural changes of the surface membrane of cancer cells would help to explain the pathogenesis and development of gastric cancer.