Gametes, also known as “sex cells,” are an organism’s reproductive cells. These cells are called ova or egg cells in females; in males, gametes are called sperm. Essentially, a gamete is a haploid cell — a cell that contains 23 chromosomes, half the normal 46 — that fuses with another haploid cell for the purpose of reproduction (called fertilization). These cells carry one copy of a chromosome from each parent, and are responsible for carrying half of the genetic information for one individual.
Egg cells mature in the ovaries and are larger and non-motile (meaning they don’t move on their own). Sperm, by contrast, is highly motile, and develops in the testes. During fertilization, the sperm and the egg cells fuse to form a new diploid organism with the full 46 chromosomes.
Gametes are formed by gametogenesis in both males and females. Gametogenesis that occurs in males is referred to as “spermatogenesis”;, in females it is known as “oogenesis.” During gametogenesis, immature germ cells undergo meiosis, or division, to produce four haploid cells.
Types of gametes
Anisogamy or heterogamy is the sexual reproduction process involving the fusion of two gametes which differ in size or form. The smaller gamete is the male’s sperm, while the larger cell is the female’s egg.
Gametes can also be classified by their size. Microgametes tend to be smaller, extremely motile, and produced in large quantities (such as a male’s sperm). Macrogametes, by contrast, are larger, non-motile, and produced in smaller numbers (such as a female’s ova).
History of gametes
Dutch microbiologist Antonie van Leeuwenhoek was the first one to discover spermatozoa back in 1677. Over 100 years later, Karl Ernst von Baer discovered the mammalian ovum in 1827. His colleague, Oscar Hertwig, later observed the fusion of the ova and spermatozoa in 1876 in a starfish. However, it wasn’t until German cytologist Eduard Strasburger that gametes got their name.Back to Glossary