Mitosis is named after the Greek word for a loom's warp thread
When Walther Flemming watched chromosomes condensing into threads during cell division, he named the process mitosis in 1882, from Greek mitos, the warp thread on a loom. The process copies a cell's entire genome into two identical nuclei, and nearly every cell in the human body was made this way.
Mitosis is the stage of the eukaryotic cell cycle in which duplicated chromosomes are split between two new nuclei, keeping the chromosome number unchanged. The DNA is copied beforehand, during the S phase of interphase, leaving each chromosome as two identical sister chromatids held at the centromere by cohesin proteins. Afterward, cytokinesis divides the cytoplasm and organelles roughly equally between the two daughter cells.
The stages run through prophase, prometaphase, metaphase, anaphase and telophase, with an extra preprophase in plants. Chromosomes condense into visible shapes. In animals the nuclear envelope dissolves into small vesicles and the nucleolus, the ribosome factory, vanishes. Microtubules reach in from opposite poles, grip the centromeres and line the chromosomes up across the middle, then pull the sisters apart toward opposite ends. New envelopes form around each set, and the chromosomes relax again. Live imaging now lets researchers watch this happen in real time.
Not all organisms do it the same way. Animal cells generally perform an open mitosis, breaking down the nuclear envelope, and usually round up into near-spheres first; fungi typically run a closed mitosis inside an intact nucleus. The main human exceptions are egg and sperm cells, made by meiosis, while bacteria and archaea divide by binary fission.
The discovery was gradual. In 1835 the German botanist Hugo von Mohl described cells multiplying by division in the green alga Cladophora, a model that eventually beat Matthias Schleiden's rival idea with help from Robert Remak and others. In animals, division was observed in frog, rabbit and cat corneas in 1873 and first described by the Polish histologist Waclaw Mayzel in 1875, though Otto Butschli and others also have claims. Errors carry real costs: dividing into three or more cells can produce embryos that fail to implant, and faulty divisions can cause mutations from which some cancers arise.
Source: Mitosis
