So what happens is, within this particular cell, each of these fibers attaches onto each one of these respective identical cysticromatides. And so following cytokinesis, after metaphase two of meiosis, we formed the following two normal X cells. Notice that these two X cells are normal because they contain the proper number of chromosome 21. They contain one chromosome 21 each. But what happens in this case? Because the age of this XL is high, the likelihood that nondisjunction takes place is also high.