An outline of eukaryotic meiosis. DNA is replicated in S phase. For the two pairs of chromosomes shown here, this generates four sets of sister chromatids. The homologs are aligned in meiosis I, joined by recombination (crossovers not shown), then segregated. In meiosis II, the sister chromatids segregate into the haploid cell products. (See also Figure 2-12, right.)