Gametesare an organism's reproductive cells. They are also referred to as sex cells.Female gametes are called ova or egg cells, and male gametes are called sperm.Gametes are haploid cells, and each cell carries only one copy of eachchromosome. These reproductive cells are produced through a type of celldivision called meiosis. During meiosis, a diploid parent cell, which has twocopies of each chromosome, undergoes one round of DNA replication followed bytwo separate cycles of nuclear division to produce four haploid cells. Thesecells develop into sperm or ova. The ova mature in the ovaries of females, andthe sperm develop in the testes of males. Each sperm cell, or spermatozoon, issmall and motile. The spermatozoon has a flagellum, which is a tail-shapedstructure that allows the cell to propel and move. In contrast, each egg cell,or ovum, is relatively large and non-motile. During fertilization, aspermatozoon and ovum unite to form a new diploid organism.