The eukaryota, including animals, plants and fungi all share a separation of nucloplasm and genetic material from the cytoplasm effected by a membrane structure, the nuclear envelope. The nuclear envelope has great significance in the maintenance of the structure of the nucleus and in the regulation of its function. The structure of the nuclear envelope and transport across it are highly organized and many of its functions and properties appear to be conserved across the kingdoms. However, there are also key differences; for instance, during cell division, the nuclear envelope of most higher organisms breaks down resulting in what is known as an ‘open’ mitosis. However, in contrast, yeast and other fungi undergo a closed mitosis where the nuclear envelope does not break down and chromosome segregation and separation occurs within the nucleoplasm. Similarly, while animals and fungi possess discrete centrosomes (microtubule organizing centres, known as spindle pole bodies in yeast) to which microtubules are attached, such structures are absent in plants and the entire NE appears able to act to bind and organize microtubules.