Staining of midbody ring in human cell line CaCo-2 (HPA058265)
Scale bar represents 10µm
The cytokinetic bridge is a structure present during the last stage of cell division, the cytokinesis. It is composed of tubulin filaments protruding from the cleavage furrow. The width and length of the cytokinetic bridge is dependent on the progression of the cytokinesis, continuously shrinking while progressing. In the latest stage of cytokinesis the bridge is cleaved and the cells are separated.
The cleavage furrow is characterized as an invagination at the cell division site. It acts as a "purse string" during the separation of the two daughter cells and vanishes as soon as the cytokinetic bridge is formed.
The midbody is part of the cytokinetic bridge and is located at the tip of the cytokinetic bridge of both daughter cells. It consists of tightly bundled microtubules which embed the midbody ring. The midbody is the site for many cytokinesis-related processes including cytoskeleton remodeling or degradation of cell cycle regulators.
The midbody ring is a circular structure that mainly consists of actin filaments and is embedded in the space between the midbodies of the daughter cells. It is mainly responsible for the cleavage of the cytokinetic bridge, thus finishing the process of cytokinesis.
Cytokinetic bridges and its substructures are annotated by characteristic features. The most common observed staining are the microtubule filaments at the contacting pieces of the two dividing cells. The midbody staining is characterized by an exclusive staining of the tips of the microtubule filaments at the contact surface whereas the midbody ring appears as circular structure in the space between the two midbodies. The cleavage furrow is difficult to detect as it can only be seen before the cytokinetic bridge is formed. It is visible as a staining along the membranes of the two daughter cells.