Mitosis

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Interphase
Phase in which the cell is not dividing
Longest phase accounting for about 90% of the cycle
Chromosomes are elongated and appear as a mass of material called chromatin
Although cell is not dividing, they are very active in other ways
Produces new organelles and forms many chemicals necessary for growth.
During the later stages, chromosomes make identical copies of themselves. 
Prophase
Chromosomes begin to contract and become visible as double stranded structures.  Each strand is called a chromatid. The double stranded chromosomes are held together at the point called a centromere.
Nucleolus breaks down.  This is the region where ribosomes are made.
Fibres called spindle fibres appear in the cytoplasm
Metaphase
Nuclear membrane breaks down
Spindles move to each end of the pole.
A spindle fibre from each end of the pole of the cell attaches to each centromere.
The chromosomes line up across the equator of the cell.
Anaphase

Telophase

 
This is the shortest phase of mitosis only lasting a couple of minutes.
The spindle fibres contract.  This causes the centromere to split.
One chromatid from each of the double stranded chromosome is pulled to opposite poles of the cell.
Now the cell has 8 chromosomes.

 

The 4 chromosomes at each pole begin to elongate and become difficult to distinguish
The spindle fibres break down
One or more nucleolus begin to reform
A nuclear membrane forms around each clump of chromatin at each of the two poles.
The original nucleus has divided into two identical nuclei.
Mitosis is now complete.

Cell division follows immediately after mitosis.  The process of cell division is called Cytokinesis.                     

To see image of mitosis click on this link http://www.biology.arizona.edu/cell_bio/tutorials/cell_cycle/cells3.html

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