Abstract
Cadmium ions at 5 to 100μg/ml induced morphological alterations in Euglena gracilis grown in zinc-sufficient media. The average cell volume was used as a parameter of morphological abnormality. Many types of abnormal-shaped cells were observed when the cadmium-ion concentration was high enough to increase the average cell volume. Most abnormal-shaped cells were starfish-shaped. Scanning electron microscopic observations clearly showed that the structure of the pellicle of starfish-shaped cells was not different from that of normal dividing cells and that these starfish-shaped cells, which were polynucleated and in the process of cytokinesis, resulted from abnormal cytokinesis, but not from cell fusion.
