Fig. 8. Analysis of ER and chromatin organisation in zVEID-treated apoptotic cells. HeLa cells were induced into apoptosis in the presence of zVEID.FMK, then processed for fluorescence microscopy (A) or EM (B-D). (A) A confocal optical section through the centre of a zVIED-treated apoptotic HeLa cell, labelled with anti-KDEL antibodies (red), phalloidin (green) and DAPI (blue). Condensed chromatin remains enclosed within an intact nuclear envelope that labels strongly with anti-KDEL (arrowheads). Actin is located principally around the cell periphery [abundant actin is also found in retraction cables at the cell base (data not shown)]. (B) A section through the centre of a zVEID-treated apoptotic HeLa cell. Chromatin (ch) is closely associated with the inner leaflet of the intact nuclear envelope (arrows), and does not relocate to the cell periphery. Surface blebs remain relatively small. (C) High magnification of a zVEID-treated apoptotic HeLa cell showing chromatin (Ch) abutting a dilated nuclear envelope [in zVEID-treated apoptotic HeLa cells, nuclear envelope lumen diameter was significantly (P=0.001) greater than in standard apoptotic cells, increasing from 19.4 nm (s.e.m.=0.9) to 34.4 nm (s.e.m.=3.3)]. Well-preserved mitochondria (m) are found throughout the cytoplasm. (D) ER membranes form whorls and interconnecting tubular arrays in zVEID-treated apoptotic HeLa cells. ER tubules are also significantly dilated [mean diameter in standard apoptotic HeLa cells was 23.7 nm (s.e.m.=2.8), increasing to 44.9 nm (s.e.m.=4.9; P=0.001) in zVEID-treated apoptotic HeLa cells]. Bars: 5 µm (A,B) and 500 nm (C,D).