Cytokinesis is the last step in a long line of cell formation processes. The cell must grow and prepare to divide in the interphase, which contains phases G1, S and G2. Then the cell undergoes mitosis in a series of four phases to split the nucleus into identical copies of the genetic material. The four phases are prophase, metaphase, anaphase and telophase. During mitosis, the four sets of chromosomes split into two, attach to the microtubules and move to the opposite sides of the cell.
Cytokinesis, also called C phase in the cell cycle, is the physical division of the cell into two identical daughter cells. The cells now contain the same genetic information encoded on their chromosomes. Cytokinesis happens after telophase, when a new nuclear envelope begins to form around the two groups of chromosomes on either end of the cell. The exception to even division of cytoplasm is oogenesis, where the creation of an ovum (an egg) in the ovary takes almost all of the cytoplasm and organelles, leaving the other half to die.
Cytokinesis in animal cells begins by a cleavage furrow forming down the equator of the cell. The cleavage furrow is the visible pinching together and closing off of each individual cell's new membrane. The new cells continue to pull apart from one another until the membranes have completely separated. This is possible because the chromosomes have unwound in their new cells and the microtubules do not have a strong hold on the two cells to keep them together.
Cytokinesis in plant cells is not as fluid due to the presence of a rigid cell wall in plants. Rather than pinching and separating, plants form an additional cell wall between the two newly divided cells. The formation of a new plant wall includes five stages: the creation of microtubules for wall support, inserting vesicles into the wall for tubular transport, deposition of membrane sheets into the cell wall, recycling the excess "building materials" and fusion with the perpendicular existing cell walls.