Figure 2

TEM micrographs showing toxic effects of 10^-4 M Pb on ultrastructure of the root meristematic cells of A. sativum. a: Rich parallel arrays of ER with regularly extended cisternae (24 h). b: Increased vesicles from dictyosomes and ER, with some incorporated into bigger vacuoles; and accumulation of electron-dense granules containing Pb ions in vacuoles (arrows). c: Electron-dense granules localized on the surface of membranes in mitochondria. d: Obvious decrease in mitochondrial cristae and vesiculation of dictyosomes and ER (48 h). e. Vacuolization of dictyosomes (72 h). f. Plasmolysis and some electron-dense granules from vesicles relocated into cytoplasm due to loss of vesicle membrane function (72 h). C = cytoplasm, CM = cytoplasm membrane, CW = cell wall, D = dictyosome, ER = endoplasmic reticulum, EDG = electron-dense granules, M = mitochondria, N = nucleus, V = vacuole, Ve = vesicle. Bar = 0.25 μm