FISH is, therefore, useful in identifying the origin of duplications and marker chromosomes. There are 46 chromosomes, or 23 pairs of chromosomes, present in every cell except the eggs and sperm which have 23 chromosomes. Chromosomes 1 through 22 are referred to as autosomes. They are present in both males and females. The 23rd pair of chromosomes, referred to as the sex chromosomes, differ between the sexes.
Females have two copies of the X chromosome, one from each parent.
Males receive an X chromosome from the mother, and a Y chromosome from the father. Chromosome analysis requires growing cells in culture and harvesting dividing cells. Chromosomes are arranged into a karyotype based on size, shape and banding pattern. Conventionally, twenty cells are analyzed for chromosome count and morphology. Different staining techniques can be used to analyze the chromosomes.