Your body's cells obviously can't live on forever, so they need to reproduce in order to keep your body and mind functioning properly. So how does your body replenish its cells? The answer is this: by an asexual reproduction process that is used by eukaryotic cells called mitosis. Here is a very basic and brief explanation of animal cell division.
Even though interphase isn't technically included in the process of mitosis, a cell still spends ninety percent of its life in this phase. During that ninety percent, the cell grows and develops normally and carries on its usual functions. (See both eukaryotic and prokaryotic cell parts and functions in this article.) At the end of this phase the chromosomes have duplicated themselves.
The first phase of mitosis is called prophase. In this phase, the nuclear membrane of the cell disappears as well as the nucleoli. The chromosome pairs shorten and thicken and become visible under a high-powered microscope. Centrioles separate and move to the opposite poles and spindle fibers begin to grow and extend from them.
The second phase of mitosis is metaphase. During this stage, chromatid pairs line up on the equatorial plate and each paired chromosome is attached to a spindle fiber, which is in turn attached to a centromere.
Metaphase is followed by anaphase, a relatively simple phase. This is the phase in which the spindle fibers pull the duplicated chromosomes to the opposite ends of the cell.
Telophase is the last part of mitosis. Here, the chromosomes elongate back into their normal forms, and the cytoplasm begins to divide in two. The spindle fibers disappear before the nuclear membrane reforms and the nucleoli reappears. Finally, mitosis is complete when two daughter cells are formed with the same number of chromosomes.
Lastly, interphase repeats, with twenty-three pairs of chromosomes in the nuclei of the daughter cells. The cells continue to grow and develop again until the reproduction process of mitosis repeats.
A Little Beyond Basic: Mitosis is followed immediately by cytokinesis, which divides the nucleoli, cell organelles, and cell membrane. The end result is two complete, functioning daughter cells that are genetically identical to their parent cells.
*To learn more about cell division, see our article on meiosis here.
And for some really amazing photographs of a cell during mitosis, go to this link- http://www.en.wikipedia.org/wiki/Mitosis
Life Science, Glencoe/McGraw-Hill, a division of The McGraw Hill Companies, Inc.