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Cover   As part of the inheritance process in animal cells, the single-copy Golgi apparatus fragments at the onset of mitosis. The fragments begin to disperse during prophase, and redistribution throughout the cell is essentially complete by metaphase. At the onset of cytokinesis, the fragments congregate in the juxtanuclear region where they fuse to reform the interphase Golgi ribbon. The process of Golgi division (or dictyokinesis) was first described by Perroncito (1910. Arch Ital. Biol. 54, 307-345), and a particularly good example of this process is described in one of several papers on the subject contributed by Ludford (1924. Proc. R. Soc. Lond. 97, 50-60). Shown on the left side of the cover montage is Ludford's diagrammatic scheme on the behavior of the Golgi apparatus during mitosis.
  A modern example of the organization of Golgi membranes during mitosis is shown in the upper right confocal immunofluorescence image, where a PtK1 cell has been double immunolabeled for microtubules (pseudocolor gray) and the Golgi apparatus (pseudocolor white). The electron micrograph in the lower right panel shows that the individual fragmented mitotic Golgi membranes are not dispersed Golgi stacks but clusters of vesicles and tubules (termed mitotic clusters, two examples are seen in the lowest part of the micrograph; Zeligs and Wollman, 1979. J. Ultrastruct. Res. 66, 53-77; Lucocq et al., 1987. J. Cell Biol. 104, 865-874). The significance of this tubulo-vesicular transformation of the stack, although dramatic, is still unclear, especially because it does not occur in plants or fungi (Griffing, 1991. J. Electron Microsc. Tech. 17, 179-199). Recent evidence suggests that the mitotic fragmentation and dispersal processes reflect the reorganization of Golgi membranes by the emerging mitotic spindle (note organization of Golgi membranes around the spindle pole region in the light and electron micrographs), an event that may ensure more accurate inheritance of the Golgi apparatus during cytokinesis (Shima et al., 1998. J. Cell Biol. 141(4).D.T. Shima, N. Cabrera-Poch,

B. Jämsä, and G. Warren

Electron micrograph reprinted by permission from Biochimica et Biophysica Acta (1998. Biochim. Biophys. Acta Mol. Cell. Res. Special Issue on the Golgi Complex [in press]), copyright 1998 Elsevier Scientific. Fluorescence image adapted from Journal of Cell Biology (1998. J. Cell Biol. 141(4)), copyright 1998 The Rockefeller University Press.