The crossing over takes place in

The crossing-over takes place in Pachytene.
Pachytene is the stage of meiotic prophase that immediately follows the zygotene and is characterized by paired chromosomes thickened and visibly divided into chromatids and by the occurrence of crossing-over.
During this stage, exchanges of chromosome material between maternal and paternal homologous chromosomes occur by crossing over. At the points of crossing over, bridges (chiasmata) are seen in variable numbers. Depending on the chiasmata, different aspects of the chromosomes can be observed.