So before meiosis actually takes place and before this male individual can produce sperm cells, those chromosomes must replicate themselves during the process of interface. And so the x chromosome is replicated to produce this identical x chromosome, and the y chromosome is also replicated to produce this identical cystochromatid. So normally, what should happen during normal conditions is during metaphase one of meiosis, these pairs basically line up at the equator of our cells. So in humans, we're going to have 23 pairs of these chromosomes line up at the middle. And then during anaphase, if these connections are formed correctly, these 23 pairs of chromosomes are basically moved to opposite poles. Now, if nondisjunction takes place, what that means is, once again, we fail to form this fiber attachment.