synapsis

The pairing of homologous chromosomes during *prophase of the first division of meiosis. The nature of the force that causes homologues to be drawn to each other is not known, but pairing is a very exact process, commencing with the pairing of the *centromeres and continuing with pairing of *chromomeres at various points along the length of the homologues. During the process, contraction of the chromosomes continues and they become closely coiled around each other to form bivalents.