Human chromosomes. Coloured scanning electron micrograph (SEM) of a pair of human chromosomes. One chromosome of the pair has replicated during cell division to form an identical copy, or chromatid. Chromatids are joined by the centromere, the region of a chromatid that also divides it into two asymmetrical arms". Chromosomes are present in the nucleus of every cell of the body. They consist of genetic material, DNA (deoxyribonucleic acid), in association with proteins. Most human cells contain 46 chromosomes, 23 inherited from the mother and 23 from the father. Magnification: x13,550 at 6x6cm size."