Ultrastructural changes in A549 cells treated with 100 nM/L staurosporine. A: Transmission electron microscopy image of an untreated A549 control cell. The nuclear chromatin was homogenized (asterisk), the intracytoplasmic rough endoplasmic reticulum was dense (arrows), and there were a large number of ribosomes (arrow heads). A large number of healthy microvilli were observed at the cell surface (5,000 ×). B: Transmission electron microscopy image of an A549 cell treated with 100 nM staurosporine for 24 h. Typical signs of apoptosis were observed. The nuclear chromatin coagulated to a plate-shaped structure and gathered in the vicinity of the nuclear membrane (asterisk), the cytoplasmic mitochondria were swollen (arrow heads), the endoplasmic reticulum expanded (arrows). The number of microvilli on the cell surface decreased (5,000 ×).