What was the X chromosome called before?
These chromosomes would come to be known as the sex chromosomes, X and Y.
Is the X the female gene?
The 23rd pair of chromosomes are called the sex chromosomes, and those chromosomes are called either X or Y. Males have one X sex chromosome and one Y sex chromosome, while females have two X sex chromosomes. The genes on the X chromosomes are important for how the body grows and functions.