Gamete

The gametes (from the Greek γαμετή gametḗ 'wife' or γαμέτης gamétēs 'husband') are the haploid sex cells of multicellular organisms originated by meiosis from germ cells (or meiocytes in the case of diploid cells).

Human beings reproduce sexually, this means that it takes two sex cells that unite to form the new individual. These sex cells are called gametes and there are two kinds: male or sperm and female or ovules.

Features

Gametes receive different names depending on the sex of the carrier and the kingdom (animal, plant) to which they belong. In animals, the gametes come from a specific cell line called the germ line, differentiated in early stages of development, and the female is called the ovum and the male the spermatozoon; and once fused they produce a cell called a zygote or called a fertilized egg that contains two sets of chromosomes, which is why it is diploid. In plants, the female gamete is called the oosphere, and the pollen is the male gametophyte, inside the which form the male gametes that fertilize the oosphere.

Gametes are cells made up of a single set of chromosomes (they have a unique version of the genetic information that will determine the physical characteristics of the individual) that during fertilization will fuse with another gamete of the opposite sex to form the zygote. The formation of gametes is called gametogenesis. The organs that produce gametes are called gonads in animals, and gametangia in plant organisms.

The cell resulting from the fusion of the gametes brings together the chromosomes of both, so the gametes are usually haploid cells. In diploid organisms, such as animals, the formation of gametes involves a process of meiosis, with its corresponding chromosome reduction. In haplodiplontic organisms, such as plants, the gametes are produced by the haploid phase (gametophyte), while it is the diploid phase (sporophyte), produced precisely from fertilization, which produces spores by meiosis.

Research

One of the newest lines of research is the formation of artificial gametes in laboratories. This advance could undoubtedly mean a before and after in assisted reproduction techniques.
Different research groups have developed to date artificial gametes in animal models from somatic cells, but it is a field still under development in humans due to various reasons (ethical, scientific, reliability...) The biggest problem to date is that identical gametes to the somatic cell have not been able to be created, only similar.

Disparity

In some protist organisms and in fungi the gametes are morphologically and physiologically identical, although there may be a definite genetic difference. In evolution, however, there is a very clear tendency to distinguish more and more a female gamete, generally large and immobile, and a male gamete, small and mobile.

In plants and algae there are three cases that correspond to as many degrees of manifestation of the indicated trend:

• Isogamy: gametes are identical, usually mobile.
• Anisogamy: one of the gametes is still and bigger.
• Oogamy: the immobile gamete, feminine, is rich in nutritious reserves, which inherits after fertilization the zygote, and which facilitate the first development of a new multicellular organism, until it is able to ensure for itself its nutrition.