(A) Representative images of the same BSC1 cell visualized by bright field phase contrast illumination during prophase, metaphase or cytokinesis (B) Ortogonal fluorescent views corresponding to the distribution of EGFP-CAAX in the same cell imaged using the confocal spinning head. The stacks along the z-axis correspond to sequential optical sections acquired 0.25 µm apart. The panels show the fluorescence signal along the z-axis (top) along a single confocal plane positioned approximately in the middle of the cell. Bar, 10 µm. (C) The mask (light blue) corresponds to the position of the EGFP-CAAX signal calculated for each confocal plane (see Methods). The outline of the outer boundary determined for any given plane defines the enclosed area for such plane (dark blue). (D) Three-dimensional rendition comparing the distribution of EGFP-CAAX (green) and the calculated cell volume (blue).