At anaphase of meiosis, some chromosomes lag behind. They are called laggards. This is due to

Centromere is very important structures for binding of chromosomes to the spindle fibres. Centromeres possess kinetochore discs for binding to the spindle fibres. Chromosomes lacking centromere are called acentric (laggard) chromosomes. Since acentric chromosomes lack centromere, they cannot bind to spindle fibres and are frequently lost by one of the daughter cells produced. This gives rise to unbalanced progeny cells and unbalanced gametes are produced.