The following images illustrate
the key stages of meiosis. Clicking on each of the
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see the Flash movie for the following sequence of images,
Meiosis begins with Meiosis I. The first stage in Meiosis I is prophase I. During this stage the DNA condenses into chromosomes.
During prophase I, homologous chromosomes pair up and exchange sections of DNA. This is called recombination or crossing over.
This is followed by metaphase I where the connected pairs of chromosomes align at the middle of the cell.
After the pairs of chromosomes are aligned, anaphase I begins. During this stage, the microtubules, or spindle fibers, pull the homologous chromosomes apart and move them to opposite ends of the cell.
Telophase I is next. Here the spindle fibers are broken up, new nuclear membranes form, the chromosomes uncoil, and the cell divides into two daughter cells.
The next phase of meiosis is called Meiosis II. This begins with prophase II. During this stage the chromosomes condense once again, the nuclear membrane breaks down, and the spindle apparatus forms in each of the two new cells.
This is followed by metaphase II. Here the spindle fibers attach to the chromosomes and again align them at the middle of the new cells.
Next, during anaphase II, the sister chromatids are pulled to opposite ends of the cells, and the cells elongate.
Finally, during telophase II, the sister chromosomes uncoil, new nuclear membranes form, and the two cells are divided again, forming four new haploid cells called gametes.