androgen


androgen
androgenic /an'dreuh jen"ik/, adj.
/an"dreuh jeuhn, -jen'/, n. Biochem.
any substance, as testosterone or androsterone, that promotes male characteristics.
[1935-40; ANDRO- + -GEN]

* * *

Any of a group of hormones that mainly influence the development of the male reproductive system.

The main and most active androgen is testosterone, produced by cells in the testes. Androgens produced in smaller quantities, mainly by the adrenal gland but also by the testes, support the functions of testosterone. Androgens cause the normal changes of puberty in boys' bodies and then influence sperm-cell formation, sexual interest and behaviour, and male pattern baldness. Females produce trace quantities of androgens, mostly in the adrenal glands, as well as in the ovaries.

* * *

Introduction

      any of a group of hormones that primarily influence the growth and development of the male reproductive system.

Production.
      The predominant and most active androgen is testosterone (q.v.), which is produced by the male testes. The other androgens, which support the functions of testosterone, are produced mainly by the adrenal cortex—the outer substance of the adrenal glands—and only in relatively small quantities. Trace quantities of androgens are found in the female blood plasma. It is believed that the adrenal glands produce most of these small amounts. The ovaries, which normally secrete the female hormones known as estrogens, also produce minute amounts of androgens.

      In the male, the interstitial cells of Leydig, located in the connective tissue surrounding the sperm-producing tubules of the testes, are responsible for the production and secretion of androgens. In male animals that breed only seasonally, such as migratory birds and sheep, Leydig cells are prevalent in the testes during the breeding season but diminish considerably in number during the nonbreeding season. The actual secretion of androgens by these cells is controlled by luteinizing hormone (LH) from the pituitary gland.

Effects.
      Androgens are needed for the development of the male reproductive system. Without injections of testosterone, males that have been castrated prior to adolescence and sexual maturity do not develop functioning adult reproductive organs. Androgens given to normal males tend to increase the size of the reproductive organs; castration performed on males that have already reached maturity causes the organs to shrink and to stop functioning. Androgens are also necessary for the formation of sperm cells and for the maintenance of sexual interest and behaviour.

      Other effects of androgens upon the male body are diversified. The growth of pubic hair and of facial and chest hair and the regression of scalp hair, or baldness, are influenced by androgens. During adolescence, androgens lengthen and thicken the male vocal cords (vocal cord), causing voice deepening; they also enhance bone growth and increase the number and thickness of muscle fibres in the male body. Other growth patterns that androgens stimulate are kidney weight and size, the increase of protein in bone tissue, the regeneration of red blood cells, the presence of pigments in the skin, and the increased activity of sweat and sebaceous (oil-producing) glands.

* * *


Universalium. 2010.

Look at other dictionaries:

  • Androgen — Androgen, also called androgenic hormone or testoid, is the generic term for any natural or synthetic compound, usually a steroid hormone, that stimulates or controls the development and maintenance of male characteristics in vertebrates by… …   Wikipedia

  • androgen — ANDROGÉN, Ă, androgeni, e, adj. Care se referă la caracterele sexuale masculine, care provoacă în organism modificări cu caracter masculinizant. – Din fr. androgène. Trimis de ana zecheru, 21.07.2007. Sursa: DEX 98  androgén adj. m., pl.… …   Dicționar Român

  • androgen — n. 1. a hormone, such as testosterone or androsterone, that promotes development and maintenance of typical male sexual characteristics. They are mostly produced in the testes. [WordNet 1.5 +PJC] …   The Collaborative International Dictionary of English

  • androgen — androgen. См. андроген. (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.

  • androgen — (n.) male sex hormone, 1936, from ANDRO (Cf. andro ) + GEN (Cf. gen) …   Etymology dictionary

  • androgen — [an′drō jən, an′drəjən] n. a type of natural or artificial steroid that acts as a male sex hormone androgenic [an′drəjen′ik] adj …   English World dictionary

  • Androgen — Androgene (von griechisch andro „männlich“; gen „erzeugend“) sind Sexualhormone, die eine virilisierende (von lateinisch virilis „männlich“) Wirkung besitzen. Strukturformel von Androstan (10β,13β Dimethyl gonan). Ihr Grundgerüst ist das… …   Deutsch Wikipedia

  • Androgen — A male sex hormone that promotes the development and maintenance of the male sex characteristics. The major androgen is testosterone. * * * Generic term for an agent, usually a hormone ( e.g., androsterone, testosterone), that stimulates activity …   Medical dictionary

  • androgen — noun Etymology: International Scientific Vocabulary Date: 1936 a male sex hormone (as testosterone) • androgenic adjective …   New Collegiate Dictionary

  • androgen — General term for any male sex hormone in vertebrates …   Dictionary of molecular biology


Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”

We are using cookies for the best presentation of our site. Continuing to use this site, you agree with this.