Cell Division - Mitosis

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cartoon of mitosis and meiosis
Mitosis and meiosis

Normal cell division in all cells, except germ cells, occurs by 2 mechanical processes that initially divide the nucleus then the cell cytoplasm. This process produces two (daughter) cells that should be genetically identical to the parent cell.

Germ cells, oocyte and spermatozoa, undergo meiotic cell division.

  • Mitosis segregation of chromosomes and formation of 2 nuclei
  • Cytokinesis splitting of the cell as a whole into 2 daughter cells
  • Recent Nobel Prizes- 2001 Cell Cycle, 2002 Cell Death

Mitosis of the single zygote produces how many cells in the adult?
Mark Hill.jpg
Not a straightforward calculation! Cells through development and in the adult divide and die influenced by cell type, genetics and environment. In the adult, most tissues though would have a relatively contestant balance between loss and gain in cell numbers. A recent paper has attempted to estimate the number for humans[1] "In particular, the reported total cell number of a human being ranges between 1012 and 1016 and it is widely mentioned without a proper reference. ...A current estimation of human total cell number calculated for a variety of organs and cell types is presented. These partial data correspond to a total number of 3.72 × 1013."

Cell Division Links: Meiosis | Mitosis | Lecture - Cell Division and Fertilization | Spermatozoa Development | Oocyte Development | Fertilization | Zygote | Genetics

Some Recent Findings

  • The nucleoporin ELYS/Mel28 regulates nuclear envelope subdomain formation in HeLa cells[2] "In open mitosis, the nuclear envelope (NE) reassembles at the end of each mitosis. This process involves the reformation of the nuclear pore complex (NPC), the inner and outer nuclear membranes, and the nuclear lamina. In human cells, cell cycle-dependent NE subdomains exist, characterized as A-type lamin-rich/NPC-free or B-type lamin-rich/NPC-rich, which are initially formed as core or noncore regions on mitotic chromosomes, respectively. Although postmitotic NE formation has been extensively studied, little is known about the coordination of NPC and NE assembly. ...Our data show, that ELYS/Mel28 plays a role in NE subdomain formation in late mitosis."
More recent papers
Mark Hill.jpg
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This table shows an automated computer PubMed search using the listed sub-heading term.

  • Therefore the list of references do not reflect any editorial selection of material based on content or relevance.
  • References appear in this list based upon the date of the actual page viewing.

References listed on the rest of the content page and the associated discussion page (listed under the publication year sub-headings) do include some editorial selection based upon both relevance and availability.

Links: References | Discussion Page | Pubmed Most Recent | Journal Searches

Search term: Mitosis

D Patel, G Gorelik, B Richardson Protein Phosphatase 5 Contributes to the Overexpression of Epigenetically Regulated T-Lymphocyte Genes in Patients with Lupus. Lupus (Los Angel): 2016, 1(3); PubMed 28239687

Eyemen G A Kheir, Torsten Krude Non-coding Y RNAs associate with early replicating euchromatin concordantly with the origin recognition complex (ORC). J. Cell. Sci.: 2017; PubMed 28235841

Marisa Simon, Fahmi Mesmar, Luisa Helguero, Cecilia Williams Genome-wide effects of MELK-inhibitor in triple-negative breast cancer cells indicate context-dependent response with p53 as a key determinant. PLoS ONE: 2017, 12(2);e0172832 PubMed 28235006

Shi-Zheng Wu, Ying-Lan Li, Wei Huang, Wen-Feng Cai, Jialiang Liang, Christian Paul, Lin Jiang, Zhi-Chao Wu, Meifeng Xu, Ping Zhu, Yigang Wang Paracrine effect of CXCR4-overexpressing mesenchymal stem cells on ischemic heart injury. Cell Biochem. Funct.: 2017; PubMed 28233339

Douglas C Wallace, Marie T Lott Leber Hereditary Optic Neuropathy: Exemplar of an mtDNA Disease. Handb Exp Pharmacol: 2017; PubMed 28233183



This movie shows a cell dividing by mitosis with a fluorescently labelled protein that is located at the kinetochores and along the axes of the chromosome arms. This allows you to see the chromosomes and the linking region (kinetochore) between chromosome pairs and the mitotic spindle microtubules.[3]

Mitosis 01 icon.jpg
Page | Play
Mitosis Links: MP4 movie | Cell Division - Mitosis | Week 1 | Lecture - Cell Division and Fertilization | Movies
Links: MCB Movie - The stages of mitosis and cytokinesis in an animal cell

Cell Changes

  • Nucleus
    • Chromosome condensation
    • Nuclear envelope breakdown
  • Cytoplasm
    • Cytoskeleton reorganization
    • Spindle formation (MT) Contractile ring (MF)
    • Organelle redistribution
  • Mitosis Energy
    • Cell division uses up a lot of energy, so cells ensure they have enough resources to complete the job before committing to it.

Mitosis Phases

  • Based on light microscopy of living cells light and electron microscopy of fixed and stained cells
  • 5 Phases - prophase, prometaphase, metaphase, anaphase, and telophase
    • Cytokinesis 6th stage overlaps the end of mitosis

MBC The stages of mitosis and cytokinesis in an animal cell


  • not a mitotic phase (discussed in cell cycle)
  • Chromosomes dispersed in nucleus
  • Gene expression
  • Cytoskeleton and cell organelles - Distributed and functioning
  • Mitochondria undergo independent proliferation/division

Chromosome Changes

Mitosis fl.jpg


Mammalian cell - prophase
Mammalian cell - prophase[4]
  • Chromosome DNA has been earlier duplicated (S Phase)
  • Chromosomes begin condensing
  • Chromosome pairs (chromatids) held together at centromere
  • Microtubules disassemble
  • Mitotic spindle begins to form

Spindle Apparatus

  • 3 sets of microtubules - (+) ends point away from centrosome at each pole.
  1. astral microtubules - anchor the pole end in position
  2. kinetochore microtubules - connected to chromosomes
  3. polar microtubules - form the structure of the spindle apparatus

Spindle Apparatus EM | Spindle Apparatus | MBC Movie- Microtubule dynamics during mitosis

At end of prophase nuclear envelope breaks down


  • Microtubules now enter nuclear region
  • Nuclear envelope forms vesicles around mitotic spindle
  • Kinetochores form on centromere attach to some MTs of spindle

Dynamic instability and the capture of chromosomes

Centromeric attachment of microtubules

At end of prometaphase chromosomes move to metaphase plate


Mitosis - Metaphase
  • Kinetochore MTs align chromosomes in one midpoint plane.
    • Astrin is a spindle-associated protein required for chromosome alignment at the metaphase plate.[5]

Proposed alternative mechanisms for chromosome congression

Metaphase ends when sister kinetochores separate


Chromosome motility anaphase
  • Separation of sister Kinetochores
  • shortening of Kinetochore microtubules pulls chromosome to spindle pole.
  • Katanin is a microtubule-severing complex involved with this stage of microtubule dynamics.[6]

Experiment - during anaphase A chromosomes move poleward along stationary kinetochore microtubules, which coordinately disassemble from their kinetochore ends

Anaphase ends as nuclear envelope (membrane) begins to reform.


Mitosis - Telophase
  • Chromosomes arrive at spindle poles
  • Kinetochore MTs lost
  • Condensed chromosomes begin expanding
    • Continues through cytokinesis

Links: Figure 19-41 Microtubule dynamics during mitosis | Figure 19-34. The stages of mitosis and cytokinesis in an animal cell | Cytokinetic abscission: cellular dynamics at the midbody

Cleavage of Zygote

Mouse zygote mitosis[7]

Mouse zygote mitosis metaphase.jpg Mouse zygote mitosis anaphase.jpg
First metaphase First anaphase

Cleavage of the zygote forms 2 blastomeres and is cleavage with no cytoplasm synthesis.

  • special "embryonic" cell cycle S phases and M phases alternate without any intervening G1 or G2 phases (MSMSMSMS, adult MG1SG2) therefore individual cell volume decreases

Cell division within these cells is initially synchronous (at the same time), then becomes asynchronously (at different times).

  • slow- centre cells, larger fast- peripheral cells

Links: Zygote | Cell Division - Mitosis | Movie - Early Cell Division | Movie - Week 1 Cell Cleavage | Carnegie stage 1


  • Division of cytoplasmic contents
  • Contractile ring forms at midpoint under membrane
  • Microfilament ring - contracts forming cleavage furrow
    • myosin II is the motor
  • Eventually fully divides cytoplasm

Links: Cytokinesis | Cytokinesis in Plants

Mitotic Spindle

Spindle assembly motors 01.jpg

Spindle assembly motors[8]

Microtubule (MT)-bound motors promote bipolar spindle formation, whereas chromosome-associated motors drive proper kinetochore orientation and chromosome movement to the equator.

Box 1 Box 2 Box 3 Box 4 Box 5
Motor-dependent mechanisms establish bipolarity as Eg5 (kinesin-5) motors slide antiparallel microtubules apart with their minus ends leading and their plus ends directed toward the spindle equator. Minus end–directed motors such as dynein move microtubules poleward with their minus ends leading, thereby incorporating K-fibers into the spindle and focusing spindle poles. Kinetochore-associated dynein transports chromosomes along astral microtubules toward the spindle poles from the periphery. Plus end–directed chromokinesins (kinesin-4 and -10) eject chromosome arms outward. CENP-E (kinesin-7) transports unattached kinetochores toward the equator along spindle microtubules. MTOC, microtubule organizing centre.

Cell Organelles


  • Divide independently of cell mitosis
  • distributed into daughter cells


  • localise at spindle poles

Mitosis peroxisomes 01.jpg

Peroxisome (red) location at Interphase (a) and during Mitosis (b and c)[9]

Endoplasmic Reticulum

  • Associated with nuclear membrane.


  • 2 processes - disassembly and reassembly[10]
  • Golgi stack undergoes a continuous fragmentation process
  • fragments are distributed into daughter cells
  • are reassembled into new Golgi stacks


  • Unstacking - mediated by two mitotic kinases (cdc2 and plk)
  • Vesiculation - mediated by COPI budding machinery ARF1 and the coatomer complex


  • Fusion - formation of single cisternae by membrane fusion
  • Restacking - requires dephosphorylation of Golgi stacking proteins by protein phosphatase PP2A


  1. Eva Bianconi, Allison Piovesan, Federica Facchin, Alina Beraudi, Raffaella Casadei, Flavia Frabetti, Lorenza Vitale, Maria Chiara Pelleri, Simone Tassani, Francesco Piva, Soledad Perez-Amodio, Pierluigi Strippoli, Silvia Canaider An estimation of the number of cells in the human body. Ann. Hum. Biol.: 2013, 40(6);463-71 PubMed 23829164
  2. Michaela Clever, Tomoko Funakoshi, Yasuhiro Mimura, Masatoshi Takagi, Naoko Imamoto The nucleoporin ELYS/Mel28 regulates nuclear envelope subdomain formation in HeLa cells. Nucleus: 2012, 3(2);187-99 PubMed 22555603
  3. Penny A Tavormina, Marie-George Côme, Joanna R Hudson, Yin-Yuan Mo, William T Beck, Gary J Gorbsky Rapid exchange of mammalian topoisomerase II alpha at kinetochores and chromosome arms in mitosis. J. Cell Biol.: 2002, 158(1);23-9 PubMed 12105179
  4. Russan NM. Let's Build a Spindle. ASCB Image & Video Library. 2008;CYT-190. Available at: http://cellimages.ascb.org/u?/p4041coll12,521
  5. Anja K Dunsch, Emily Linnane, Francis A Barr, Ulrike Gruneberg The astrin-kinastrin/SKAP complex localizes to microtubule plus ends and facilitates chromosome alignment. J. Cell Biol.: 2011, 192(6);959-68 PubMed 21402792
  6. Dong Zhang, Gregory C Rogers, Daniel W Buster, David J Sharp Three microtubule severing enzymes contribute to the "Pacman-flux" machinery that moves chromosomes. J. Cell Biol.: 2007, 177(2);231-42 PubMed 17452528
  7. Khursheed Iqbal, Seung-Gi Jin, Gerd P Pfeifer, Piroska E Szabó Reprogramming of the paternal genome upon fertilization involves genome-wide oxidation of 5-methylcytosine. Proc. Natl. Acad. Sci. U.S.A.: 2011, 108(9);3642-7 PubMed 21321204 | PMC2132672 | PNAS
  8. Rebecca Heald, Alexey Khodjakov Thirty years of search and capture: The complex simplicity of mitotic spindle assembly. J. Cell Biol.: 2015, 211(6);1103-11 PubMed 26668328
  9. Simone Kredel, Franz Oswald, Karin Nienhaus, Karen Deuschle, Carlheinz Röcker, Michael Wolff, Ralf Heilker, G Ulrich Nienhaus, Jörg Wiedenmann mRuby, a bright monomeric red fluorescent protein for labeling of subcellular structures. PLoS ONE: 2009, 4(2);e4391 PubMed 19194514 | PMC2633614 | PLoS One.
  10. Danming Tang, Kari Mar, Graham Warren, Yanzhuang Wang Molecular mechanism of mitotic Golgi disassembly and reassembly revealed by a defined reconstitution assay. J. Biol. Chem.: 2008, 283(10);6085-94 PubMed 18156178



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Cite this page: Hill, M.A. 2017 Embryology Cell Division - Mitosis. Retrieved February 28, 2017, from https://embryology.med.unsw.edu.au/embryology/index.php/Cell_Division_-_Mitosis

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