pach·y·tene 
(păkĭ-tēn′)
(păkĭ-tēn′)n.
The third stage of the prophase of meiosis, during which the homologous chromosomes become short and thick and divide into four distinct chromatids.
[French pachytène : Greek pakhus, thick + French -tène, ribbon (from Latin taenia; see TAENIA).]