Gonad
A reproductive gland (ovary or testis) that produces germ cells (gametes). In embryonic life, the gonad in males and females is initially identical. This gonad is said to be "indifferent" before it differentiates into a definitive testis or ovary. An indifferent gonad becomes a testis if the embryo has a Y chromosome, but if the embryo has no Y chromosome, the indifferent gonad becomes an ovary. Thus, an XY chromosome complement leads to testes while an XX chromosome complement leads to ovaries. There are people with just one X chromosome and no Y. They are girls with Turner syndrome who are infertile. The absence of a Y chromosome permits the indifferent gonad to become an ovary. However, two X chromosomes are needed for the ovary to function normally. The male gonad is the testicle (or testis), located behind the penis in a pouch of skin (the scrotum). The testicles produce and store sperm, and they are also the body's main source of male hormones (testosterone). These hormones control the development of the reproductive organs and other male characteristics, such as body and facial hair, low voice, and wide shoulders. The word "testis" is Latin for "witness." In ancient times, a person providing testimony might validate it by holding the scrotum, his or another man's. "And the servant put his hand under the thigh of Abraham his master, and swore to him concerning the matter." (Genesis 24:9) The female gonad, the ovary or "egg sac", is one of a pair of reproductive glands in women. They are located in the pelvis, one on each side of the uterus. Each ovary is about the size and shape of an almond. The ovaries have two functions: they produce eggs (ova) and female hormones. Each month, during the menstrual cycle, an egg is released from one ovary. The egg travels from the ovary through a fallopian tube to the uterus. The ovaries are the main source of female hormones (estrogen and progesterone). These hormones control the development of female body characteristics, such as the breasts, body shape, and body hair. They also regulate the menstrual cycle and pregnancy.
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An organ that produces sex cells; a testis or an ovary. [Mod. L. fr. G. gone, seed]
- female g. SYN: ovary.
- indifferent g. the primordial organ in an embryo before its differentiation into testis or ovary. See indifferent genitalia.
- male g. SYN: testis.
- streak g. SYN: gonadal streak.

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go·nad 'gō-.nad n a gamete-producing reproductive gland (as an ovary or testis)
go·nad·al gō-'nad-əl adj

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n.
a male or female reproductive organ that produces the gametes. See ovary, testis.

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go·nad (goґnad) [L. gonas, from Gr. gonos procreation] a gamete-producing gland; an ovary, testis, or ovotestis. Called also genital gland and sex gland. gonadal adj

Medical dictionary. 2011.

Look at other dictionaries:

  • Gonad — Gon ad, n.; pl. {Gonads}. [Gr. ? that which generates.] (Anat.) One of the masses of generative tissue primitively alike in both sexes, but giving rise to either an ovary or a testis; a generative gland; a germ gland. Wiedersheim. [1913 Webster] …   The Collaborative International Dictionary of English

  • gonad — gonad. См. гонада. (Источник: «Англо русский толковый словарь генетических терминов». Арефьев В.А., Лисовенко Л.А., Москва: Изд во ВНИРО, 1995 г.) …   Молекулярная биология и генетика. Толковый словарь.

  • gonad — 1880, from Mod.L. gonas (pl. gonades), coined from Gk. gone, gonos seed, act of generation, race, family, from gignesthai be born, related to genos race, birth, descent (see GENUS (Cf. genus)). Related: gonads …   Etymology dictionary

  • gonad — ► NOUN ▪ a bodily organ that produces gametes; a testis or ovary. DERIVATIVES gonadal adjective. ORIGIN Latin gonades, plural of gonas, from Greek gon generation, seed …   English terms dictionary

  • gonad — [gō′nad΄] n. [< ModL gonas (pl. gonades) < Gr gonē, a seed, generation < IE * gon < base * ĝen , to produce > GENUS] an organ or gland in animals that produces reproductive cells; esp., an ovary or testis gonadal adj …   English World dictionary

  • gonad — gonadal, gonadial /goh nay dee euhl/, gonadic /goh nad ik/, adj. /goh nad, gon ad/, n. Anat. a sex gland in which gametes are produced; an ovary or testis. [1875 80; < NL gonad (s. of gonas), equiv. to gon GON + ad AD1] * * * ▪ …   Universalium

  • 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, spermatozoon and egg cells are gametes. Although medically the… …   Wikipedia

  • gonad — UK [ˈɡəʊnæd] / US [ˈɡoʊˌnæd] noun [countable] Word forms gonad : singular gonad plural gonads medical a sex organ that makes cells used in producing babies. In men this sex organ is called a testicle, and in women it is called an ovary …   English dictionary

  • gonad — noun Etymology: New Latin gonad , gonas, from Greek gonos Date: 1880 a reproductive gland (as an ovary or testis) that produces gametes • gonadal adjective …   New Collegiate Dictionary

  • gonad(o)- — [L. gonas, gen. gonadis gonad, from Gr. gonos procreation] a combining form denoting relationship to the gonads …   Medical dictionary

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