[Biologic effects of hyperthermia and radiation on gastric cancer cells (SGC-7901) in vitro. II. Ultrastructural changes of cells].

Different characteristic damages of the SGC-7901 gastric adenocarcinoma cells were studied by electron microscopy 1, 36, 72, 96 and 120 hours after heating and radiation in vitro. The visible damages, such as the enlarged mitochondria, increase of lysosomes and perichromatin granules could be shown 1 hour after heating (43 degrees C for 30 min) but no visible damages of the cells were shown until 36 hours following radiation (500 rad). In order to study the ultrastructural changes of the gastric cancer cells in mitosis after heating and radiation, we have used the new method of ultrastructural research in selecting and observing the M cell in vitro and found loosened structure of chromosome and disappearance of microtubules 1 hour following hyperthermia. At the same time, no apparent abnormalities of the mitotic cells were observed after radiation. It is the chief cause of division delay in heat injured cells. However, the chromosomes and microtubules of the new mitotic cells could recover 36 hours after heating (43 degrees C for 30 min). After radiation, the giant cells and abnormal morphologic changes of cells gradually increase and the living cells decrease. Unexpectedly, the division of a few giant cells is observed 72 hours after heating and radiation.