Gametes are the reproductive cells called sperm in men and ovum in women. They are located in the sex glands, which are also called the gonads. The gonads in males are the testes and in females they are the ovaries. We speak of “a gamete”, a male name.

The word “gamete” was coined from the ancient Greek names, “γαμ? Της”, gametes and “γαμ? Τις”, gametes, which refer to husband and wife respectively.

Gametes are haploid cells, that is, they contain a complete collection of our chromosomes, in a single copy each.

In women

Female gametes, called ova, are made by the ovaries. We have two, one left and one right. The ovaries make one egg per month. This ovum has a nucleus surrounded by cytoplasm, bounded by a membrane. The ovum is therefore a cell.

These reproductive cells, with a dimension of 0,1 mm in diameter, are haploid. They have only one copy of each chromosome, conversely to a diploid cell, which contains two homologs of each chromosome. They contain 22 autosome chromosomes + 1 sex chromosome). Female gametes are made during oogenesis, the ovarian cycle, the time between periods of menstruation.

Before reaching puberty, a woman has what are called ovarian follicles. It is an aggregate of spherical cells in the ovaries, containing what is called an oocyte, (an unformed egg) that is released during ovulation.

It is only at puberty that the follicles undergo their maturation necessary for ovulation, they then increase in size. The ovaries then function regularly and in turn produce an egg.

Thus, every month, an ovarian follicle matures, in one or the other ovary, before emitting its ovum: we then speak of ovulation. This phenomenon, which is repeated every month, when there is no fertilization, is therefore cyclical, as are menstruation.

The egg is immobile and it is a fertilizable gamete. If there has been no fertilization, the egg released by the ovary is sucked through the pinna of a proboscis and is passively drawn. It passes through the uterus and is then eliminated by the vulva.

During her lifetime, a woman produces a limited number of eggs, around 400. The production of eggs, as well as the periods stop around age 50, this phenomenon is called menopause.

In humans

Male gametes in other words spermatozoa are mobile cells that are more than 60 micrometers (0.06 mm) long, of which only 5 micrometers are for the head.

These sperm, which are shaped like a frog’s tadpole, are made up of three parts: the head, the middle part and the tail. The oval-shaped head contains a nucleus which itself hosts the chromosomes. They are 23 chromosomes called autosomes + 1 chromosome specific to the sexual coding, that is to say which determines the sex of the person, man or woman.

The middle piece contains mitochondria and nutrients that allow sperm to move around. Finally, the sperm has a long tail, called a flagellum, which will allow it to propel itself through the long path of the woman’s uterus in order to reach the ovary and fertilize it.

In men, the production of sperm, known as spermatogenesis, begins at puberty, during adolescence and continues until their death. The spermatogenesis cycle lasts an average of 64 days, so it takes about two and a half months for the testis to make a sperm. And the testicles make it continuously. Although production is subject to variation, the average production is considered to be 100 million sperm per day.

The testes produce sperm, but also nutrient fluid produced by the seminal vesicles and the prostate. This mixture forms semen. It is made up of 90% nourishing fluid and 10% sperm.

Gametes are specialized cells whose function is to ensure sexual reproduction. For fertilization to take place, a sperm must therefore come into contact with the egg and merge with it. A single sperm is usually accepted by the egg, which automatically closes as soon as it has entered the way for the others.

During a sexual relation, they can unite with the gametes of the opposite sex and one speaks then of fertilization, which will perhaps produce a new human being.

There are a multitude of cases where both male and female gametes can exhibit abnormalities. Either in their production, absence or not enough spermatozoa, or ova for fertilization. Sperm not strong enough to reach the egg, placing the egg in the wrong place.

There are also genetic abnormalities, which involve a future malformation or genetic disease of the fetus, this is the case with Trisomy 21. Frequently the embryo is not carried to term by the body of the woman who detects an abnormality.

Screenings are done at different stages of pregnancy to prevent the risk of genetic abnormalities.

Gamete donation concerns couples of childbearing age who must seek medically assisted procreation, either because one of the spouses suffers from medically diagnosed infertility, or because there is a risk of transmission of a particularly serious disease to the child or to one of the spouses.

Like all other donations of elements and products of the human body, the donation of gametes is an act of solidarity, governed by the main principles of the law of bioethics: anonymity, gratuity and consent.

The number of couples waiting for a donation of gametes and the lack of donations is very real. The number of couples registered on the waiting lists of authorized centers is increasing every year. A 2017-2021 ministerial action plan for procreation gives priority to the development of gamete donation to move towards national self-sufficiency.