Cytokinesis refers to the process of a single cell dividing its cytoplasm to develop two daughter cells. This process typically occurs as the final stage of cell division after mitosis and helps aid in chromosome number protection throughout cellular regeneration. It can be found in plant and animal cells.
Plant cell cytokinesis occurs when plant cells divide by forming cross walls between the two daughter cells. The presence of cell walls in plants makes this process greatly different from how it works in animal cells. The cell plate comes from the fusion of membrane vesicles that are targeted along a particular plant phargmoplast. A phargmoplast is a thin barrier that forms around the spindle. In the beginning, the phargmoplast acts as hollow cylinder that delivers vesicles to outside areas of the developing cell plate.
Once the phargmoplast has taken form, centrifugal growth in the cell plate begins due to the new vesicles fusing. These small vesicles fuse at the metaphase plate in order to form the cell plate. Eventually, the cell plate expands over the cell in order to join with the plasma membrane.
Animal cell cytokinesis is more complex process than that of the plant cells, as animal cellular regeneration is structured by a contractile ring. The contractile ring behaves similarly to a muscle by contracting the actin filaments until the ring is tightened, cutting the cell into two pieces. This process is also known as the cleavage furrow due to the occurrence of the cleavage of one cell into two cells.
There are four main stages of this process in animal cells. The first step occurs when the contractile ring defines the position around which it will form. The ring must first form along the axis of the spindle that is responsible for separating the chromosomes.
Second, the actin filaments must be assembled. These filaments are essential, as they form the contractile ring. The second step is also when the additional proteins are formed; these are essential to facilitating ring contractions.
The third step occurs when the ring actually begins contraction. Animal cell contraction begins when the myosin motor moves the actin filaments around each other, similar to that of a muscle contraction. The last step occurs when the ring contracts to its smallest size, causing separation and refusion of the plasma membranes.
In order for proper genetic information to be passed, all stages must be completed. Cell division may only occur when all other criteria has been properly established. Once the proper conditions are set, the process is concluded.