Fig. 5. Electron micrographs of Bir1p-overexpressing cells and bir1 cells. (A-B) Cells overexpressing Bir1p that had been treated with 0.8 mM H₂O₂ for 4 hours do not show any apoptotic hallmarks. (C-F) bir1 cells show strong invaginations of the nuclear envelope (black arrows in C), a very prominent endoplasmatic reticulum (white arrowheads in D and F), chromatin condensation at the nuclear envelope (black arrowheads in D), and tiny vesicles on the outer face of the plasma membrane (grey arrowheads in E). In few cells chromosome segregation defects were also detected (white arrows in F). Bars, 500 nm.