Plant cell mitosis. Light micrograph of root tip cells from an onion (Allium sp.) undergoing cell division (mitosis). From top left to bottom right: the chromosomes condense and appear as long thread-like structures (prophase). They then align along the centre of the cell (metaphase). Each chromosome consists of two identical sister chromatids that separate and are pulled to opposite ends of the cell (anaphase). Nuclear membranes then form around the two daughter nuclei as the chromosomes de-condense (telophase). The cell then divides (cytokinesis). Magnification: x1000 when printed 10 centimetres wide.