English: Homologous chromosomes are not paired in leptotene, but SYCP3 starts to localize to centromeres and arms. In zygotene, synapsis initiates from the non-centromeric regions and progresses as SYCP1 and central element proteins zip up SYCP3-containing chromosome axes. At late zygotene, centromeres are at last paired and synapsed, and full SC is formed along the entire chromosome in pachytene. In diplotene, the SC disassembles except at the sites where centromere pairing persists and chiasmata are formed. At diakinesis/metaphase I, SYCP3 proteins are accumulated on the centromere and a small fraction of homologous centromeres are linked by SYCP3-containing stretches, which may function in bi-orientation of homologous centromeres and attachment to the spindles for the first meiotic division.