Transient structure existing during the end of cytokinesis
The midbody is a transient structure found in
mammaliancells and is present near the end of
cytokinesis just prior to the complete separation of the dividing cells. The structure was first described by
Walther Flemming in 1891.[1]
Structure
A middle stage midbody stained with tubulin
The midbody structure contains bundles of
microtubules derived from the
mitotic spindle which compacts during the final stages of cell division. It has a typical diameter of 1
micrometre and a length of 3 to 5 micrometres.[2] Aside from microtubules it also contains various proteins involved in
cytokinesis, asymmetric
cell division, and
chromosome segregation.
The midbody is important for completing the final stages of cytokinesis, a process called
abscission.[3] 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-like signalling molecule, and can be internalised by nearby cells.[4]
This endosome is marked by
MKLP1, and can persist for up to 48 hours once internalised into another cell.[4] It is coated in
Actin, which is slowly degraded by the internalising cell.