Cr in its hexavalent form was also found to inhibit cell growth and morphogenesis in short-term treated Micrasterias cells (Fig. 1h; see also Volland et al., 2012). Further, cell division rates were stagnant during long-term treatment (Fig. 5c) and the chloroplast appeared dark and contracted while lobe tips were vacuolated (Fig. 1g). Net-photosynthesis reached negative levels and the electron transport kinetics is disturbed (Fv/Fm = 0.54; Fig. 5a and b). Cell vitality was reduced to 75.33% of that of controls (Table 1). Depositions of Cr in a compound with Fe and O were detected via EELS and ESI in specific, bag-like structures in the inner side of the cell wall during a recent study (Volland et al., 2012). Additionally, ultrastructural alterations were observed in the chloroplast and secretory activity was inhibited.