Affixes

This ending appears in four terms for the successive steps in the first stage of division of a cell, the prophase, in which the chromosomes separate. The four steps are leptotene (Greek leptos, fine, thin, delicate), in which each chromosome becomes visible as two fine threads (chromatids); zygotene (Greek zugon, yoke), in which homologous chromosomes begin to pair; pachytene (Greek pakhus, thick), in which the paired chromosomes shorten and thicken, the two chromatids of each separate, and exchange of segments between chromatids may occur; and diplotene (Greek diplous, double), in which the paired chromosomes begin to separate into two pairs of chromatids.