Gland

Gland

A gland is an organ in an animal's body that synthesizes a substance for release such as hormones or breast milk, often into the bloodstream (endocrine gland) or into cavities inside the body or its outer surface (exocrine gland).

Types

Glands can be divided into two groups:
* Endocrine glands — are glands that secrete their product directly onto a surface rather than through a duct.
* Exocrine glands — secrete their products via a duct, the glands in this group can be divided into three groups:
** Apocrine glands — a portion of the secreting cell's body is lost during secretion. "Apocrine gland" is often used to refer to the apocrine sweat glands, however it is thought that apocrine sweat glands may not be true apocrine glands as they may not use the apocrine method of secretion.
** Holocrine glands — the entire cell disintegrates to secrete its substances (e.g., sebaceous glands)
** Merocrine glands — cells secrete their substances by exocytosis (e.g., mucous and serous glands). Also called "eccrine."The type of secretory product of an Exocrine gland may also be one of three categories:
* Serous glands — secrete a watery, often protein-rich product.
* Mucous glands — secrete a viscous product, rich in carbohydrates (e.g., glycoproteins).
* Sebaceous glands — secrete a lipid product.

Formation

Every gland is formed by an ingrowth from an [epithelium|epithelial] surface. This ingrowth may from the beginning possess be a tubular structure, but in other instances glands may start as a solid column of cells which subsequently becomes tubulated.

As growth proceeds, the column of cells may divide or give off offshoots, in which case a compound gland is formed. In many glands the number of branches is limited, in others (salivary, pancreas) a very large structure is finally formed by repeated growth and sub-division. As a rule, the branches do not unite with one another, but in one instance, the liver, this does occur when a reticulated compound gland is produced. In compound glands the more typical or secretory epithelium is found forming the terminal portion of each branch, and the uniting portions form ducts and are lined with a less modified type of epithelial cell.

Glands are classified according to their shape.
* If the gland retains its shape as a tube throughout it is termed a tubular gland.
* In the second main variety of gland the secretory portion is enlarged and the lumen variously increased in size. These are termed alveolar or saccular glands.

pecific glands

A list of human "exocrine glands" is available here.

A list of human "endocrine glands" is available here.

Crypts of Lieberkuhn

The Crypts of Lieberkuhn in the lower gastrointestinal tract are also referred to as "glands."


=Additional

References

*1911


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  • gland — gland …   Dictionnaire des rimes

  • gland — [ glɑ̃ ] n. m. • XIIe; lat. glans, glandis 1 ♦ Fruit du chêne, akène contenant une graine farineuse, enveloppé à sa base dans une cupule. Sangliers qui se nourrissent de glands. 2 ♦ (1538) Anat. Renflement antérieur de la verge. ⇒vulg. nœud.… …   Encyclopédie Universelle

  • gland — GLAND, glanduri, s.n. (anat.) Porţiunea terminală a penisului. – Din fr. gland. Trimis de gall, 13.09.2007. Sursa: DEX 98  GLAND s.n. Porţiunea terminală a penisului. [< fr. gland]. Trimis de LauraGellner, 02.07.2006. Sursa: DN  GLAND s …   Dicționar Român

  • gland — GLAND. s. m. Fruit de chesne & de quelques autres arbres semblables. Il y aura bien du gland cette année. on engraisse les cochons de gland. les Poëtes disent que les premiers hommes vivoient de gland. On appelle fig. Gland, Certain ouvrage de… …   Dictionnaire de l'Académie française

  • gland — Gland, Glans, glandis. Gland de chesne, Roburneae fruges. Chesne qui porte gland, Quercus glandifera. Une forest où il croist du gland, Glandaria sylua. Toute sorte de gland, Balanus …   Thresor de la langue françoyse

  • gland — gland1 [gland] n. [Fr glande < OFr glandre < L glandula, tonsil, dim. of glans (gen. glandis), acorn (< IE base * gwel , oak, acorn > Gr balanos)] 1. any organ or specialized group of cells that produces secretions, as insulin or bile …   English World dictionary

  • Gland — Gland, n. [F. glande, L. glans, glandis, acorn; akin to Gr. ? for ?, and ? to cast, throw, the acorn being the dropped fruit. Cf. {Parable}, n.] [1913 Webster] 1. (Anat.) (a) An organ for secreting something to be used in, or eliminated from, the …   The Collaborative International Dictionary of English

  • gland — [glænd] n [Date: 1600 1700; : French; Origin: glande, from Latin glans acorn ] an organ of the body which produces a substance that the body needs, such as ↑hormones, ↑sweat, or ↑saliva ▪ the pituitary gland …   Dictionary of contemporary English

  • gland — [ glænd ] noun count a part of your body that produces a chemical substance that your body needs: the thyroid gland …   Usage of the words and phrases in modern English

  • gland — 1690s, from Fr. glande (O.Fr. glandre, 13c.), from L. glandula gland of the throat, tonsil, dim. of glans (gen. glandis) acorn, nut; acorn shaped ball, from PIE root *gwele acorn (Cf. Gk. balanos, Armenian kalin, O.C.S. zelodi acorn; Lith …   Etymology dictionary

  • gland — gland. См. железа. (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.

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