Leptotene The chromosomes appear as thin long threads and have a beaded appearance due to the presence of chromomeres Pachytene Dissolution of the synaptonemal complex takes place in zygotene. The characteristic phenomenon during pachytene is the exchange of chromosomal segments, i.e., the recombination of genes or crossing over Diplotenes Tetrads formation takes place in pachytene stage. In diplotene the paired chromosomes begin to separate but remains united at the points of interchange of chiasma