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Every cell in the human body, apart from enucleated red blood cells and the haploid gametes, has 23 pairs of chromosomes ( for a total of 46 ).

One copy of each pair is inherited from the mother and the other copy is inherited from the father.

The first 22 pairs of chromosomes ( referred to as autosomes ) are numbered from 1 to 22, and are arranged from largest to smallest in a karyotype ( see figure ).

The 23rd pair of chromosomes are the sex chromosomes.

Normal females have two X chromosomes, while normal males have one X chromosome and one Y chromosome.