The chromosomes are depicted (by rearranging a microphotograph) in a standard format known as a "karyogram" or "idiogram": in pairs, ordered by size and position of centromere for chromosomes of the same size. This may be used for many purposes; such as, to show genetic disease, what sex the animal is and its diploid number. In humans, cytologists have used karyotypes to help identify genetic abnormalities a baby might have before it is born.