Editing Mitosis (section)

=== Forms of mitosis ===
The mitosis process in the cells of eukaryotic organisms follows a similar pattern, but with variations in three main details. "Closed" and "open" mitosis can be distinguished on the basis of [[nuclear envelope]] remaining intact or breaking down. An intermediate form with partial degradation of the nuclear envelope is called "semiopen" mitosis. With respect to the symmetry of the [[spindle apparatus]] during metaphase, an approximately axially symmetric (centered) shape is called "orthomitosis", distinguished from the eccentric spindles of "pleuromitosis", in which mitotic apparatus has bilateral symmetry. Finally, a third criterion is the location of the [[central spindle]] in case of closed pleuromitosis: "extranuclear" (spindle located in the cytoplasm) or "intranuclear" (in the nucleus).<ref name="Raikov-1994"/>

<gallery mode="nolines">
File:Mitosis classification closed intranuclear pleuromitoses.svg|closed <br> intranuclear <br> pleuromitosis
File:Mitosis classification closed extranuclear pleuromitoses.svg|closed <br> extranuclear <br> pleuromitosis
File:Mitosis classification closed orthomitoses.svg|closed <br> orthomitosis
File:Mitosis classification semiopen pleuromitoses.svg|semiopen <br> pleuromitosis
File:Mitosis classification semiopen orthomitoses.svg|semiopen <br> orthomitosis
File:Mitosis classification open orthomitoses.svg|open <br> orthomitosis
</gallery>

Nuclear division takes place only in cells of organisms of the [[eukaryotic]] domain, as [[bacteria]] and [[archaea]] have no nucleus. Bacteria and archaea undergo a different type of division.<ref>{{Cite web |last=Hogan |date=August 23, 2011 |title=Archaea |url=https://eol.org/docs/discover/archaea |website=Encyclopedia of Life}}</ref><ref>{{Cite web |title=Binary Fission and other Forms of Reproduction in Bacteria |url=https://cals.cornell.edu/microbiology/research/active-research-labs/angert-lab/epulopiscium/binary-fission-and-other-forms-reproduction-bacteria |website=Cornell College of Agriculture and Life Sciences}}</ref> Within each of the eukaryotic [[Eukaryote#Five supergroups|supergroups]], mitosis of the open form can be found, as well as closed mitosis, except for unicellular [[Excavata]], which show exclusively closed mitosis.<ref>{{cite journal | vauthors = Boettcher B, Barral Y | title = The cell biology of open and closed mitosis | journal = Nucleus | volume = 4 | issue = 3 | pages = 160–5 | year = 2013 | pmid = 23644379 | pmc = 3720745 | doi = 10.4161/nucl.24676 }}</ref> Following, the occurrence of the forms of mitosis in eukaryotes:<ref name="Raikov-1994"/><ref>R. Desalle, B. Schierwater: ''Key Transitions in Animal Evolution.'' CRC Press, 2010, p. 12, [https://books.google.com/books?id=LYDRBQAAQBAJ&pg=PA12 link] {{Webarchive|url=https://web.archive.org/web/20190102095006/https://books.google.de/books?id=LYDRBQAAQBAJ&lpg=PP1&hl=en&pg=PA12 |date=2019-01-02 }}.</ref>

*'''''Closed intranuclear pleuromitosis''''' is typical of [[Foraminifera]], some [[Prasinophyceae|Prasinomonadida]], some [[Kinetoplastida]], the [[Oxymonadida]], the [[Haplosporidia]], many fungi ([[chytrid]]s, [[oomycete]]s, [[zygomycete]]s, [[ascomycete]]s), and some [[Radiolaria]] ([[Spumellaria]] and [[Acantharea|Acantharia]]); it seems to be the most primitive type.
*'''''Closed extranuclear pleuromitosis''''' occurs in [[Trichomonadida]] and [[Dinoflagellata]].
* '''''Closed orthomitosis''''' is found among [[diatom]]s, [[ciliate]]s, some [[Microsporidia]], unicellular [[yeast]]s and some multicellular [[fungi]].
*'''''Semiopen pleuromitosis''''' is typical of most [[Apicomplexa]].
*'''''Semiopen orthomitosis''''' occurs with different variants in some amoebae ([[Lobosa]]) and some green flagellates (e.g., [[Raphidophyte|Raphidophyta]] or ''[[Volvox]]'').
*'''''Open orthomitosis''''' is typical in [[mammals]] and other [[Metazoa]], and in [[land plants]]; but it also occurs in some protists.