During meiosis, terminalization of chiasmata occurs in the Diplotene stage of prophase I. At this stage, homologous chromosomes begin to separate from each other except at the chiasmata, where crossing over has occurred. Terminalization refers to the movement of chiasmata towards the ends (telomeres) of the chromosomes, facilitating their proper segregation. This process is crucial for ensuring genetic diversity and accurate chromosome disjunction. Recognizing the timing of terminalization aids in understanding chromosomal behavior during meiosis and related genetic disorders.

Reference: Gray’s Anatomy, Standring S, 42nd Edition.