Plants, like all other eukaryotes, have a nuclear envelope (NE) which separates the nucleoplasm and genetic material from the cytoplasm. In electron micrographs, the plant nuclear envelope resembles that of cells of other kingdoms. It is a double-membrane structure, is perforated by nuclear pores and it is linked to surrounding endoplasmic reticulum (ER). Unlike yeast and most other unicells, but in common with most eukaryotes, plants have an open cell division and the NE breaks down in mitosis. When this occurs, the disrupted NE membrane appears to integrate with ER; however, the membranes of the plant mitotic apparatus are complex. The context of the plant NE varies greatly from cell to cell; in many cells, it is appressed between a large vacuole and the plasma membrane and surrounded by very little cytoplasm. In other cells-especially meristematic cells, where cell division is taking place, it is much more prominent and the nucleus is central and surrounded by cytoplasm.