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A gonad, sex gland, or reproductive gland[ 1 ] is a mixed gland and sex organ that produces the gametes and sex hormones of an organism. Female reproductive cells are egg cells, and male reproductive cells are sperm. [ 2 ] The male gonad, the testicle, produces sperm in the form of spermatozoa. The female gonad, the ovary, produces egg cells.
Gametes are an organism's reproductive cells, also referred to as sex cells.[2] The name gamete was introduced by the German cytologist Eduard Strasburgerin 1878. [3] Gametes of both mating individuals can be the same size and shape, a condition known as isogamy. By contrast, in the majority of species, the gametes are of different sizes, a ...
The gonadal ridge, in turn, develops into a gonad. This is a testis in the male and an ovary in the female. At first, the mesonephros and gonadal ridge are continuous, but as the embryo grows the gonadal ridge gradually becomes pinched off from the mesonephros. However, some cells of mesonephric origin join the gonadal ridge.
A sex organ, also known as a reproductive organ, is a part of an organism that is involved in sexual reproduction. Sex organs constitute the primary sex characteristics of an organism. Sex organs are responsible for producing and transporting gametes, as well as facilitating fertilization and supporting the development and birth of offspring.
The evolution of sexual reproduction contains two related yet distinct themes: its origin and its maintenance. Bacteria and Archaea ( prokaryotes ) have processes that can transfer DNA from one cell to another ( conjugation , transformation , and transduction [ 4 ] ), but it is unclear if these processes are evolutionarily related to sexual ...
A germ cell is any cell that gives rise to the gametes of an organism that reproduces sexually. In many animals, the germ cells originate in the primitive streak and migrate via the gut of an embryo to the developing gonads. There, they undergo meiosis, followed by cellular differentiation into mature gametes, either eggs or sperm.
During fertilisation, haploid gametes come together to form a diploid zygote, and the original number of chromosomes is restored. Sexual reproduction is a type of reproduction that involves a complex life cycle in which a gamete (haploid reproductive cells, such as a sperm or egg cell) with a single set of chromosomes combines with another ...
Gonochorism. Hermaphrodite. v. t. e. Gametogenesis is a biological process by which diploid or haploid precursor cells undergo cell division and differentiation to form mature haploid gametes. Depending on the biological life cycle of the organism, gametogenesis occurs by meiotic division of diploid gametocytes into various gametes, or by mitosis.