Synapsis is the formation of a structure termed a bivalent (a pairing of homologous chromosomes) during meiotic division. The chromotids of each of the homologous chromosomes align, essentially gene for gene to form a synaptonemal complex that allows crossover (exchange of genetic material).

In contrast to mitosis, meiosis results in the reduction of the cellular genome to a haploid state. This reduction of chromosome number is achieved by a single round of DNA replication followed by two sequential rounds of nuclear and cellular division (meiosis I and meiosis II). Like mitosis, meiosis is initiated after the synthetic phase is completed and the parental chromosomes have replicated to produce identical sister chromatids. Once the cellular DNA has replicated, the chromosomes condense into daughter chromatids of the duplicated chromosome. However, the patterning of chromosomal segregation during meiosis I differs from that of mitosis in that during meiosis I homologous chromosomes...