The cytokinetic bridge is a structure that connects the daughter cells during the last stages of cytokinesis. The cytokinetic bridge is formed after complete constriction of the cleavage furrow and the contractile ring and, once stabilized, the structure of the cytokinetic bridge is independent of actin. The bridge contains tight bundles of antiparallel microtubules that overlap at a central region termed the midbody. The microtubules originate at least in part from the central mitotic spindle and provide anchoring for the plasma membrane upon invagination. The cytokinetic bridge may persist for an extended period of time, depending on cell type. The diameter of the bridge is slowly reduced by further compaction and depolymerization of the microtubules, and eventually, cytokinesis is terminated by membrane fusion and abscission of the midbody. At this stage, the microtubules of the cytokinetic bridge may provide a route for transport of factors involved in abscission.
The cytokinetic bridge can be seen as an intracellular bridge between cells that have undergone mitosis, but not yet completed cytokinesis. The length and width of the cytokinetic bridge may vary, but it is characterized by the presence of tightly bundled microtubules. In the middle of the bridge, at the position of the midbody, there is a characteristic gap in the staining of microtubules.
Read more about the proteome of the cytokinetic bridge as a substructure of microtubules.