The following concentrations were used: 15 μM CdSO4 (Cd), 1 mM K2Cr2O7 (Cr) or 40 μM Pb(NO3)2 (Pb) respectively. For long-term treatments cell cultures were treated with 600 nM Cd,10 μM Cr and 5 μM Pb. After 4 h of incubation (short-term) or 21 days (long-term) of treatment, the effects on the cells were examined with a Univar light microscope (Reichert, Vienna, Austria) and documented with a Canon Powershot A620 camera (Tokyo, Japan).