Mitosis is a process of cell replication necessary for the growth of the organism and for the substitution of "aged" cells. Upon conclusion of this process, from the original cell two cells are derived, each of which possesses the same genetic material. Above all during the growth of organisms, the cells must multiply and to do this they undergo a series of events called the cell cycle. The cell cycle has two important stages: interphase and mitosis. During interphase, the cell grows in size, doubling its DNA and preparing itself for mitosis. Mitosis involves four phases described in figures 2, 3, 4, 5 and 6. In the superior plants, mitosis occurs above all in the so-called meristem tissues. These growth tissues are found principally in the roots, in the shoots and in the cambium. There is also another process of cell division which produces the male and female germ cells. It is called meiosis and features some important differences when compared to mitosis but is not dealt with in this article.