Essential features of meiosis

The first meiotic division is summarized in the top panels and the second meiotic division is summarized in the bottom panels. Crossing-over occurs at the 4-strand stage between pairs of non-sister chromatids. The first meiotic division precedes centromere replication, and leads to segregation of non-sister chromatids. The centromeres replicate prior to the second meiotic division, resulting in sister chromatid segregation.