The stage of prophase in meiosis in which pairing of homologous chromosomes is complete and the paired homologues may twine about each other as they continue to shorten; longitudinal cleavage occurs in each chromosome to form two sister chromatids so that each homologous chromosome pair becomes a set of four intertwined chromatids. SYN: pachynema. [pachy- + G. tainia, band, tape]
