And so what that means is what might happen is this fiber doesn't actually attach onto this chromosome. This is the chromatid here. And so what happens is this entire pair of cystochromatids, basically segregates, moved to one side and nothing moves to the other side. And so we form these two X cells, XL one and XL two, which are abnormal. They have anuploid. One of these cells lacks a copy of chromosome 21, but the other cell has not one, but two copies of chromosome 21.