Now, in individuals with Turner syndrome, they have one X sex chromosome and they lack the second sex chromosome. And the reason we use the o symbol is to basically represent the fact that we have an absence of the second Y chromosome. So let's see how this can actually arise. So once again, this can arise as a result of nondisjunction. But now let's study nondisjunction as it takes place in the male individual. So in this case, we begin by assuming we have a normal female individual.