Biological effect of high and low oxygen tension--a morphological study

1. Morphological observations were carried out on the strain HeLa cells cultured under various oxygen tension. 2. The growth of the strain HeLa cells in the present experiments was markedly inhibited when they were cultured under high oxygen tension or in nitrogen gas environment. It has been clarified that air offers the most optimal gas environment. 3. Effects of the changed gas environment on the fine structures of HeLa cells were studied by phase contrast microscope and electronmicroscope. As the results it has been found that in these cells cultured under a high oxygen tension there occurs a marked swelling of mitochondria. Under anaerobic condition, however, these cells undergo degeneration, as in oxygen environment revealing no swelling of mitochondria but rather contraction. 4. Endoplasmic reticulum (ER) of HeLa cells cultured under oxygen environment is transformed from its vesicular form to lamellar form. The mechanism of lamellar transformation of ER is obscure but no morphologic connection with nuclear, cytoplasmic and mitochondrial membranes has been detected. 5. A discussion was made on these findings concerning the changes in fine structures of the cells, with a special reference to the swelling of mitochondria and morphological changes of ER under oxygen environment.