Gametes, also called sex or reproductive cells, are haploid—they contain a single set of chromosomes. This means they have half the number of chromosomes found in most body (somatic) cells and are designed to fuse with a gamete from the opposite sex during fertilization to form a diploid zygote. In animals, the female gamete is the ovum (egg) and the male gamete is the sperm. Haploid gametes are produced by meiosis, a special type of cell division that reduces chromosome number from diploid to haploid.