Fig. 1. Large-volume tomographic reconstructions of different stages of mitosis and cytokinesis in Arabidopsis meristem cells. All of the tomographic models are cells from root meristems, except the ring phragmoplast stage, which is from an apical-meristem cell. (A) Late-anaphase (5.9x5.9x0.8 µm), which shows two opposing sets of spindle microtubules (mt; green and pink) above and between the migrating sister chomatids (ch) and vesicles (v). (B) Phragmoplast initials (5.9x5.9x0.8 µm) in which the phragmoplast microtubule array is beginning to form between the decondensing chromatin, and cell-plate-forming vesicles and cell-plate assembly matrix (not shown) accumulate at the equatorial plane. (C) Solid-phragmoplast stage (4.3x4.3x1.2 µm), with two dense sets of opposing microtubules between the forming daughter nuclei (n). The growing cell plate (cp) is surrounded by many vesicles and is sandwiched between the two sets of microtubules. (D) Transitional-phragmoplast stage (2.8x2.8x0.8 µm), which lacks a cell-plate assembly matrix and displays many short microtubules on both sides of the maturing cell plate. (E) Ring-phragmoplast stage (5.9x2.8x0.9 µm). Two dense sets of opposing microtubules flank the growing edge of cell plate, which is surrounded by many vesicles, and a cell-plate assembly matrix (not shown). The more mature central cell-plate region has fewer interacting microtubules. Scale bars, 1 µm.