Meiosis is divided into stages, much like mitosis. Unlike mitosis, however, meiosis is a two-step process, consisting of two sequential cell divisions. Therefore, one basic difference between meiosis and mitosis is that at the end of meiosis, there are haploid four progeny cells, whereas at the end of mitosis, there are two diploid progeny cells.

The two cell divisions in meiosis are called meiosis I and meiosis II. Each of these divisions is divided into the same stages as mitosis: prophase, metaphase, anaphase, and telophase. Stages are numbered according to which meiotic cell division is being discussed. For example, prophase of the first meiotic cell division is called prophase I; anaphase of the second meiotic cell division is called anaphase II.

Prophase I

Prophase of the first meiotic division is a very eventful time; to keep track of these events, prophase I has been broken up into five substages: leptonema, zygonema, pachynema, diplonema, and diakinesis. (Note: for each substage except diakinesis, the name of the substage ends with "-nema"; the adjective referring to each stage ends with "-tene", as in "a pachytene chromosome".)

Leptonema During leptonema, the chromosomes begin to condense, although they are still quite diffuse. Remember that the chromosomes (DNA) have already replicated (during S phase), so each 'chromosome' consists of two sibling chromatids. Also during leptonema, each chromosome begins to search the nucleus for its homologue. The diagram to the left represents a cell with 4 chromosomes (two homologous pairs) as it would appear during leptonema.

Zygonema In zygonema, the chromosomes continue to condense, and homologous chromosomes find each other and begin to align to each other in a process known as "rough pairing".

Pachynema In pachynema, the aligned homologous chromosomes become much more closely associated. This process is known as synapsis. (The chromosomes are said to have synapsed.) The synapsed homologous pair of chromosomes is called a tetrad, because it consists of four chromatids. It can't be observed until the next stage, but the synapsed chromosomes may undergo crossing over in pachynema. The chromosomes continue to condense.

Diplonema During diplonema, the homologous chromosomes in each tetrad begin to separate, but they remain connected at points of crossing over. Each point of crossing over is known as a chiasma (plural: chiasmata). In the diagram at left, three chiasmata are shown. Also at this stage, the nuclear envelope begins to break down.

Diakinesis Diakinesis is the last stage of prophase I. In this stage, the homologous chromosomes separate further, and the chiasmata terminalize (proceed to the end of the chromatids, then separate). Notice how this leaves chromatids that engaged in crossing over with exchanged genetic material (as indicated by the exchange of color). The nuclear envelope has completely disintegrated by this stage. The centromeres of the chromosomes become attached to spindle fibers.

The end of diakinesis marks the end of prophase I. From here, the cell progresses into metaphase I.