The stage next to zygotene wherein the homologous chromosomes shorten, thicken, and separate into four distinct chromatids joined at the centromeres.
During the first prophase of meiosis I, there are five sub-stages:
leptotene, zygotene, pachytene, diplotene and diakinesis.
Word origin: French pachytène : Greek pakhus, thick + French -tène, ribbon pachytene French pachytène : Greek pakhus, thick + French -tène, ribbon
See also: prophase I, meiosis I