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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
Male gonad (testes, left) and female gonad (ovaries, right) Males have two testicles of similar size contained within the scrotum, which is an extension of the abdominal wall. [1] Scrotal asymmetry, in which one testicle extends farther down into the scrotum than the other, is common. This is because of the differences in the vasculature's ...
These organs are located on the outside of the body, and within the pelvis. The main male sex organs are the penis and the scrotum, which contains the testicles that produce semen and sperm, which, as part of sexual intercourse, fertilize an ovum in the female's body; the fertilized ovum develops into a fetus, which is later born as an infant.
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 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.
This occurs between the time they inhabit the forming gonads on the genital ridge to the time they migrate to the basement membrane of the seminiferous cords. Gonocyte development consists of several phases of cell proliferation, differentiation, migration and apoptosis. [4] [5] The abnormal development of gonocytes leads to fertility-related ...
Sex cords are embryonic structures which eventually will give rise (differentiate) to the adult gonads (reproductive organs). [1] They are formed from the genital ridges - which will develop into the gonads - in the first 2 months of gestation (embryonic development) which depending on the sex of the embryo will give rise to male or female sex ...
In the mouse, somatic sex determination (i.e. determination of either female or male gonads) begins at embryonic day 10.5 in mice, but is not finalised until day 12.5. [10] Male somatic cell specification involves the Y-chromosome specific Sry gene, which regulates the specification of Sertoli cells and Leydig cells . [ 10 ]