Electron Microscope Studies on Isolated Plant Protoplasts

Isolated tomato fruit protoplasts have been observed to take up both tobacco mosaic virus and ferritin by the process of pinocytosis. These studies have involved electron microscopic observations on thin sections of suitably fixed and embedded material. These electron microscopic studies have also shown that very close association exists between the nucleus and chloroplasts in these protoplasts and that occasionally there are present channels extending from the plasmalemma into the cytoplasm. The implication of these results is discussed in relation to the general physiological activity of protoplasts.