It is called meiosis to one way of reproduction of the cells . The term comes from meíōsis, a Greek word that can be translated as "decrease" .
Meiosis implies that they occur two cell divisions in the framework of sexual reproduction. In this way, four cells are obtained with the amount of chromosomes bounded in half.
Specifically, meiosis allows a diploid cell (which has two series of chromosomes) is divided twice consecutively, generating four haploid cells (with half the number of chromosomes each). This reproduction process enables the creation of sperm and oocytes .
The first division is known as meiosis I , while the second is called meiosis II . In the two you can distinguish between four phases : the prophase , the metaphase , the anaphase and the telophase .
In those organisms which reproduce sexually, haploid cell fusion is performed for the formation of the diploid zygote. Therefore, meiosis is an instance prior to the development of gametes (sex cells).
It is important to keep in mind that these gametes are the only haploid cells of these species. The meiosis of certain cells gives rise to their appearance through the procedure called gametogenesis .
Meiosis, in short, causes a reduction in half the amount of chromosomes: diploid cells (which, in the human being , they have 46 chromosomes) haploid cells (23 chromosomes) are obtained. This keeps the number of chromosomes of the species in fertilization.