A transmission electron microscope study of the effects of ion etching on cells

The effects of ion etching on blood cells have previously been studied by scanning electron microscopy. This present study by transmission electron microscopy was undertaken to evaluate the effects of the etching process on the cells. Critical point dried preparations were made, etched and subsequently processed and embedded in Araldite. Examination of thin sections of erythrocytes revealed disintegration of the plasma membrane; the residual membrane destruction products formed the tips of cones produced by long etching times. The effect of etching varied in erythrocytes in the same preparation. Nucleated cells showed a similar disintegration of the plasma membrane, but membranes of mitochondria, granules, vesicles and vacuoles did not exhibit effects of etching comparable to those of the plasma membranes. After treatment with a number of different fixatives, erythrocytes on carbon-coated copper grids were also etched and examined directly in a high voltage electron microscope at 1 MV. The effects were comparable to those seen in thin sections. To study the etch rates of biological materials, the resonant frequencies of quartz crystals were measured after application of thin films of albumen and cholesterol and again after these had been etched. the ratio of the frequency changes indicated that the etch rate of albumen was approximately 2-5 times that of cholesterol. The results are discussed in the light of theories of the mechanisms involved in ion etching.