Male sex chromosomes. Coloured scanning electron micrograph (SEM) of the X and Y chromosomes in a human male, known as the sex chromosomes. Every human cell has 46 chromosomes of which 22 pairs, the autosomal chromosomes, are identical in both males and females. However in males the last pair is composed of an X (at right) and a much smaller Y chromosome (at left), while females have two X chromosomes. Chromosomes carry genetic information in the form of genes and the sex chromosomes carry genes that control offspring gender. In a male the shorter arm of the male Y chromosome (upper left) has genes for male genital development. Magnification: x5830 at 6x4.5cm size. Magnifiation: x3400 at 35mm size.