Fig. 3

Nuclei of caspase-inhibited neurons display apoptotic morphological changes. Neurons were treated with colchicine (1 µM) in the absence (left panel) or presence (right panel) of N-benzyloxycarbonyl-Val-Ala-aspartyl-fluoromethyl ketone (zVAD-fmk; 100 µM). At different time points, cultures were fixed with 2.5% glutaraldehyde for transmission electron microscopy analysis. In colchicine-treated neurons, chromatin condensed to crescent- and sphere-shaped structures. Early stages (18 hr) of chromatin condensation in caspase-inhibited neurons were characterized by compaction of DNA under the nuclear envelope. At later time points (>24 hr), lumpy, highly condensed chromatin structures were formed. The width of scale bars corresponds to2 µm.