Mitosis, or cell division, is the process by which your body grows and/or repairs itself by producing more cells.
In the first stage of mitosis, known as prophase, the cell condenses, and the chromosomes inside the cell’s nucleus replicate. The membrane which encases the nucleus also disappears.
In the second stage, metaphase, these chromosomes align along the center of the cell, held in place by structures known as microtubules. Then in the third phase, anaphase, the chromatids which make up each chromosome are pulled apart to opposite ends of the cell.
In the last phase, telophase, the microtubules disappear, new membranes form around each set out chromosomes, and the cell completes its division. The incredible gif below (courtesy of Nikon’s MicroscopyU) shows a cell going through mitosis:
This gif is sped up though. Mitosis can take anywhere from a few minutes to years or even decades, depending on the animal and what type of cell is being replicated.
For example, human skin cells can replicate in about 20-24 hours, which is why we are able to heal relatively quickly after a cut or scrape.
Human liver cells, on the other hand, take a year or more to replicate, which is why the livers of alcoholics are often destroyed by heavy alcohol consumption over an extended period of time.
The diagram below illustrates the phases of mitosis and gives a little more detail about what is happening in each phase.