The midbody is a transient structure found in

mammal Mammals () are a group of vertebrate animals constituting the class Mammalia (), characterized by the presence of mammary glands which in females produce milk for feeding (nursing) their young, a neocortex (a region of the brain), fur or ...

ian

cell Cell most often refers to: * Cell (biology), the functional basic unit of life Cell may also refer to: Locations * Monastic cell, a small room, hut, or cave in which a religious recluse lives, alternatively the small precursor of a monastery ...

s and is present near the end of

cytokinesis Cytokinesis () is the part of the cell division process during which the cytoplasm of a single eukaryotic cell divides into two daughter cells. Cytoplasmic division begins during or after the late stages of nuclear division in mitosis and meios ...

just prior to the complete separation of the dividing cells. The structure was first described by

Walther Flemming Walther Flemming (21 April 1843 – 4 August 1905) was a German biologist and a founder of cytogenetics. He was born in Sachsenberg (now part of Schwerin) as the fifth child and only son of the psychiatrist Carl Friedrich Flemming (1799–18 ...

in 1891.

Structure

The midbody structure contains bundles of

microtubules Microtubules are polymers of tubulin that form part of the cytoskeleton and provide structure and shape to eukaryotic cells. Microtubules can be as long as 50 micrometres, as wide as 23 to 27 nm and have an inner diameter between 11 an ...

derived from the

mitotic spindle In cell biology, the spindle apparatus refers to the cytoskeletal structure of eukaryotic cells that forms during cell division to separate sister chromatids between daughter cells. It is referred to as the mitotic spindle during mitosis, a pr ...

which compacts during the final stages of cell division. It has a typical diameter of 1

micrometre The micrometre ( international spelling as used by the International Bureau of Weights and Measures; SI symbol: μm) or micrometer (American spelling), also commonly known as a micron, is a unit of length in the International System of Unit ...

and a length of 3 to 5 micrometres. Aside from microtubules it also contains various proteins involved in

, asymmetric

cell division Cell division is the process by which a parent cell (biology), cell divides into two daughter cells. Cell division usually occurs as part of a larger cell cycle in which the cell grows and replicates its chromosome(s) before dividing. In eukar ...

, and

chromosome segregation Chromosome segregation is the process in eukaryotes by which two sister chromatids formed as a consequence of DNA replication, or paired homologous chromosomes, separate from each other and migrate to opposite poles of the nucleus. This segregati ...

. The midbody is important for completing the final stages of cytokinesis, a process called

abscission Abscission () is the shedding of various parts of an organism, such as a plant dropping a leaf, fruit, flower, or seed. In zoology, abscission is the intentional shedding of a body part, such as the shedding of a claw, husk, or the autotomy of a ...

. During symmetric abscission, the midbody is severed at each end and released into the cellular environment.

Role in intercellular signalling

It was long assumed that the midbody was simply a structural part of cytokinesis, and was totally degraded with the completion of mitosis. However, it is now understood that post-abscission, the midbody is converted into an

endosome Endosomes are a collection of intracellular sorting organelles in eukaryotic cells. They are parts of endocytic membrane transport pathway originating from the trans Golgi network. Molecules or ligands internalized from the plasma membrane can ...

-like signalling molecule, and can be internalised by nearby cells. This endosome is marked by MKLP1, and can persist for up to 48 hours once internalised into another cell. It is coated in

Actin Actin is a family of globular multi-functional proteins that form microfilaments in the cytoskeleton, and the thin filaments in muscle fibrils. It is found in essentially all eukaryotic cells, where it may be present at a concentration of over ...

, which is slowly degraded by the internalising cell.

Related proteins

* MKLP1 *

TEX14 Testis-expressed protein 14 is a protein in humans encoded by the TEX14 gene, and is 1497 amino acids in length. TEX14 plays a vital role in the formation of germ cells, as it is an essential component of the mammalian germ cell interphase bridge. ...

CEP55 Centrosomal protein of 55 kDa (Cep55), is a protein that in humans is encoded by the ''CEP55'' gene. Cep55 is a mitotic phosphoprotein that plays a key role in cytokinesis, the final stage of cell division. and cilia The cilium, plural cilia ...

* Aurora Kinase B

References

{{reflist Organelles Molecular biology Cell biology