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Encyclopedia > Gonad

The gonad is the organ that makes gametes. The gonads in males are the testes and the gonads in females are the ovaries. The product, gametes, are haploid germ cells. For example, sperm and egg cells are gametes. Although medically the gonad term can refer to either male gonads (testicles) or female gonads (ovaries), the vernacular, or slang use of "gonads" (or "nads") usually only refers to the testicles. A gamete (from Ancient Greek γαμετης; translated gamete = wife, gametes = husband) is a cell that fuses with another gamete during fertilization (conception) in organisms that reproduce sexually. ... Human male anatomy The testicles, known medically as testes (singular testis), are the male generative glands in animals. ... Human female internal reproductive anatomy Ovaries are a part of a female organism that produces eggs. ... Haploid (meaning simple in Greek) cells have only one copy of each chromosome. ... A spermatozoon or spermatozoan ( spermatozoa), from the ancient Greek σπέρμα (seed) and (living being) and more commonly known as a sperm cell, is the haploid cell that is the male gamete. ... A human ovum Sperm cells attempting to fertilize an ovum An ovum (plural ova) is a haploid female reproductive cell or gamete. ... Look up testes in Wiktionary, the free dictionary. ... // For ovary as part of plants see ovary (plants) An ovary is an egg-producing reproductive organ found in female organisms. ... Look up Vernacular in Wiktionary, the free dictionary. ... For other uses, see Slang (disambiguation). ...

Contents

Function

In addition to producting gametes, the gonads are a combined glands providing both exocrine and endocrine functions. The male and female gonads produce steroid sex hormones, identical to those producted by adrenal cortical cells. The major distinction is the source and relative amounts produced. Human submaxillary gland. ... Exocrine gland refers to glands that secrete their products via a duct. ... The endocrine system is a control system of ductless endocrine glands that secrete chemical messengers called hormones that circulate within the body via the bloodstream to affect distant organs. ... This article is about the chemical family of steroids. ...


Testes

Main article: Testicle

The male gonads, known as the testes or testicles, secrete the class of hormones called androgens, and produce spermatazoa. The predominant androgen in males is testosterone. Look up testes in Wiktionary, the free dictionary. ... Androgen is the generic term for any natural or synthetic compound, usually a steroid hormone, that stimulates or controls the development and maintenance of masculine characteristics in vertebrates. ... Schematic diagram of a sperm cell, showing the (1) acrosome, (2) cell membrane, (3) nucleus, (4) mitochondria, and (5) flagellum (tail) A sperm cell, or spermatozoon ( spermatozoa) (in Greek: sperm = semen and zoon = alive), is the haploid cell that is the male gamete. ... Testosterone is a steroid hormone from the androgen group. ...


Ovaries

Main article: Ovaries

In females, the female gonads, known as the ovaries, secrete the hormones estrogen and progesterone, as well as ova. The dominant estrogen is known as estradiol, which is derived from testosterone. Human female internal reproductive anatomy Ovaries are a part of a female organism that produces eggs. ... A human ovum Sperm cells attempting to fertilize an ovum An ovum (plural ova) is a haploid female reproductive cell or gamete. ... Estradiol (17β-estradiol) (also oestradiol) is a sex hormone. ...


Regulation

The gonads are controlled hormonally by luteinizing hormone (LH) and follicle-stimulating hormone (FSH) secreted by the anterior pituitary gland. The anterior pituitary gland's excretion of LH and FSH are, in turn, controlled by the hypothalamus' gonadotropin-releasing hormone. Luteinizing hormone (LH) is a hormone synthesized and secreted by gonadotropes in the anterior lobe of the pituitary gland. ... Follicle stimulating hormone Follicle stimulating hormone (FSH) is a hormone synthesised and secreted by gonadotropes in the anterior pituitary gland. ... The anterior pituitary (also called the adenohypophysis) comprises the anterior lobe of the pituitary gland and is part of the endocrine system. ... The hypothalamus links the nervous system to the endocrine system via the pituitary gland (hypophysis). ... Gonadotropin-releasing hormone 1 (GNRH1 also called LHRH) is a peptide hormone responsible for the release of FSH and LH from the anterior pituitary. ...


Development

Main article: Development of the gonads

Gonads start developing as a common anlage, in the form of gonadal ridges, and only later are differentiated to male or female sex organs. The SRY gene, located on the Y chromosome and encoding the testis determining factor, decides the direction of this differentiation. The prenatal development of the gonads is a part of the development of reproductive system and sultimately forms the testes in males and ovaries in females. ... Anlage is a fundamental principle, or a foundation for future development. ... In embryology, the gonadal ridge (or genital ridge) is the precursor to the gonads. ... A sex organ, or primary sexual characteristic, as narrowly defined, is any of those anatomical parts of the body which are involved in sexual reproduction and constitute the reproductive system in a complex organism; in mammals, these are: Female: Bartholins glands, cervix, clitoris, Fallopian tubes, labia, ovaries, Skenes... This article is about the SRY gene. ... For other uses, see Gene (disambiguation). ... The human Y chromosome is one of two sex chromosomes, it contains the genes that cause testis development, thus determining maleness. ... Testis-determining factor (TDF) is a general term for the gene (or product thereof) that results in maleness in humans and some other species. ...


In 1943, Matthew Browne started a development of gonads in a part of the development of the urinary and reproductive organs. [citation needed] In prenatal development, the urinary and reproductive organs are developed from the intermediate mesoderm. ...


  Results from FactBites:
 
YouTube - weeeeeeeeeeeee (366 words)
gonads in th lightning in the lightning and in the rain ahahahahahha
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such i hilarious video about gonads and strife....
Reproductive System - MSN Encarta (1422 words)
The primordial germ cells remain inactive in the gonads until the animal reaches sexual maturity, when the undifferentiated cells undergo a great number of normal cell divisions or mitoses.
The size of gonads increases at sexual maturity because of the great number of germ cells produced at that time; many germ cells are also produced during breeding seasons so that many animals have a seasonal increase in size of the gonads.
The functioning of both male and female gonads is under the hormonal influence of the pituitary gland.
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