During telophase I, the chromosomes arrive at separate poles and decondense. Nuclear membranes re-form around them. The cell physically divides, as in mitotic cytokinesis.

 

    The Product of Meiosis I

    Meiosis I results in two independent cells. One cell contains the maternal homologous pair, with a small segment of the paternal chromosome from crossover. The other cell contains the paternal homologous pair, likewise with a small segment of the maternal chromosome. Despite the small region of crossover in the chromosomes of each cell, the maternal sister chromatids are still quite similar, as are the paternal sister chromatids. Both cells formed by meiosis I contain a haploid amount of DNA.

 

    The cells produced in meiosis I are different from those produced in mitosis because both haploid members of the meiotic pair derive from random assortments of either the maternal or paternal chromosomes from each homologous pair (with the exception of the small crossover sections). In mitosis, the cellular division separates sister chromatids and results in diploid cells containing one maternal and one paternal copy in each diploid pair.

 

    Meiosis II

    The cells produced by meiosis I quickly enter meiosis II. These cells do not undergo DNA replication before entering meiosis II. The two cells that move from meiosis I into meiosis II are haploid—each have 23 replicated chromosomes, rather than the 46 that exist in cells entering both mitosis and meiosis I.

 

    Meiotic division II occurs through the familiar phases from meiosis I and mitosis. To distinguish the phases, they are called prophase II, metaphase II, anaphase II, and telophase II. One important difference between the events of meiosis I and II is that no further genetic reassortment takes place during prophase II. As a result, prophase II is much shorter than prophase I. In fact, all of the phases of meiosis II proceed rapidly.

 

    During meiosis II, chromosomes align at the center of the cell in metaphase II exactly the way they do in mitotic metaphase. In anaphase II, the sister chromatids separate, once again in the same fashion as occurs in mitotic anaphase. The only difference is that since there was no second round of DNA replication; only one set of chromosomes exists. When the two cells split at the end of meioisis II, the result is four haploid cells.

    Of the four haploid cells, one cell is composed completely of a maternal homologue, another of a maternal homologue with a small segment of paternal DNA from crossover in meiosis I, another complete paternal homologue, and a final paternal homologue with a small segment of maternal DNA from crossover in meiosis I. These four haploid cells are the gametes, the sperm or egg cells, that fuse together in sexual reproduction to create new individuals.