Fig. 7.

Electron micrographs of Zygnema sp. E control cells (a and b) and cells treated for 3 h with 400 mM sorbitol (c and d) or 800 mM sorbitol (e and f). (a) central part of the cell with nucleus, mitochondria and chloroplast lobe, (b) cell wall area between two adjacent cells in a filament, arrow marks the division line, (c) chloroplast with dilated thylakoid membranes, condensed cytoplasm, (d) cortical area with vesicular structures in the periplasmatic space (arrows), chloroplast with plastoglobules, (e) dense accumulation of ER, mitochondria appear ‘empty’, (f) periplasmatic space filled with vesicles. Abbreviations: Chl, chloroplast, CW, cell wall, ER, endoplasmic reticulum, M, mitochondrion, N, nucleus, PG, plastoglobules. Bars a–d 1 μm, e and f 500 nm.