So this is our cell that contains the replicated sex chromosomes. So we have two identical X chromosomes and two identical Y chromosomes. Now, to form our sperm cells, the gametes in this particular male individual meiosis has to take place. And when meiosis takes place, first these two segregate and then these two individual chromosomes segregate at the end, we produce four different possibilities. Now, two of these sperm cells have identical X sex chromosomes the other two have identical Y sex chromosomes. So that means two of the four sperm cells, or 50% of the sperm cells, have the X chromosome and the other 50%, two out of four have the Y chromosome.