gland(s): Definition and Much More from Answers.com

n.

1. 1. A cell, a group of cells, or an organ that produces a secretion for use elsewhere in the body or in a body cavity or for elimination from the body.
   2. Any of various organs, such as lymph nodes, that resemble true glands but perform a nonsecretory function.
2. Botany. An organ or a structure that secretes a substance.

[French glande, from Old French glandre, alteration of Latin glandula, diminutive of glāns, gland-, acorn.]

gland² (glănd)
n.

A device, such as the outer sleeve of a stuffing box, designed to prevent a fluid from leaking past a moving machine part.

[Origin unknown.]

A structure which produces a substance or substances essential and vital to the existence of the organism and species. Glands are classified according to (1) the nature of the product; (2) the structure; (3) the manner by which the secretion is delivered to the area of use; and (4) the manner of cell activity in forming secretion. A commonly used scheme for the classification of glands follows.

1. Morphological criteria

   1. Unicellular (mucous goblet cells)

   2. Multicellular

      1. Sheets of gland cells (choroid plexus)

      2. Restricted nests of gland cells (urethral glands)

      3. Invaginations of varying degrees of complexity

         1. Simple or branched tubular (intestinal and gastric glands)—no duct interposed between surface and glandular portion

         2. Simple coiled (sweat gland)—duct interposed between glandular portion and surface

         3. Simple, branched, acinous (sebaceous gland)—glandular portion spherical or ovoid, connected to surface by duct

         4. Compound, tubular glands (gastric cardia, renal tubules)—branched ducts between surface and glandular portion

         5. Compound tubular-acinous glands (pancreas, parotid gland)—branched ducts, terminating in secretory portion which may be tubular or acinar

         II

         Mode of secretion

         1. Exocrine—the secretion is passed directly or by ducts to the exterior surface (sweat glands) or to another surface which is continuous with the external surface (intestinal glands, liver, pancreas, submaxillary gland)

         2. Endocrine—the secretion is passed into adjacent tissue or area and then into the bloodstream directly or by way of the lymphatics; these organs are usually circumscribed, highly vascularized, and usually have no connection to an external surface (adrenal, thyroid, parathyroid, islets of Langerhans, parts of the ovary and testis, anterior lobe of the hypophysis, intermediate lobe of the hypophysis, groups of nerve cells of the hypothalamus, and the neural portion of the hypophysis)

         3. Mixed exocrine and endocrine glands (liver, testis, pancreas)

         4. Cytocrine—passage of a secretion from one cell directly to another (melanin granules from melanocytes in the connective tissue of the skin to epithelial cells of the skin)

         III

         Nature of secretion

         1. Cytogenous (testis, perhaps spleen, lymph node, and bone marrow)—gland “secretes” cells

         2. Acellular (intestinal glands, pancreas, parotid gland)—gland secretes noncellular product

         IV

         Cytological changes of glandular portion during secretion

         1. Merocrine (sweat glands, choroid plexus)—no loss of cytoplasm

         2. Holocrine (sebaceous glands)—gland cells undergo dissolution and are entirely extruded, together with the secretory product

         3. Apocrine (mammary gland, axillary sweat gland)—only part of the cytoplasm is extruded with the secretory product

         V

         Chemical nature of the product

         1. Mucous goblet cells (submaxillary glands, urethral glands)—the secretion contains mucin

         2. Serous (parotid gland, pancreas)—the secretion does not contain mucin

         ---

— Stuart Judge

See adrenal glands; alimentary system; breasts; hormones; pancreas; parathyroid glands; pituitary gland; sweating; thyroid.

n/n.pl

An organ producing a specific product or secretion.

Collection of cells or tissue that removes specific substances from the blood, alters or concentrates them, and then either releases them for further use by the body or eliminates them. Typically, the functional cells of a gland rest on a membrane and are surrounded by a meshwork of blood vessels. Endocrine, or ductless, glands (e.g., pituitary, thyroid, adrenal) discharge hormones into the bloodstream directly rather than through ducts (see endocrine system). Exocrine glands (e.g., digestive, mammary, salivary, sweat) discharge their products through ducts.

For more information on gland, visit Britannica.com.

organ that manufactures chemical substances. A gland may vary from a single cell to a complex system of tubes that unite and open onto a surface through a duct. The endocrine glands, e.g., the thyroid, adrenals, and pituitary, produce hormones that are secreted directly into the bloodstream (see endocrine system). Exocrine glands secrete their substances onto an external or internal body surface. Most exocrine glands, e.g., the salivary and lacrimal glands, release their secretions through ducts. However, some open directly onto a body surface, as in the sebaceous glands of the skin and the digestive glands of the intestinal mucosa. A simple exocrine gland may consist only of a tube lined with secretory cells. In more complex types, clumps of cells produce the secretion and a duct or system of ducts discharges the secreted material. Some glands have dual functions, e.g., the liver, pancreas, ovary, and testis produce both a secretion that is emitted through a duct and a hormone that is taken up by the blood. Such structures are called mixed glands. Among the substances produced by exocrine glands in humans are sweat, lubricants like mucus and tears, and digestive juices. There are specialized exocrine glands in the animal world that produce such substances as the shells of bird eggs, spiderwebs, and the cocoons of the silkworm larvae. Simple glands are also common in the plant kingdom. The sweet nectar of flowers and the resinous pitch of pine trees are substances produced by plant glands.

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Organs or groups of cells that take substances from the blood and change them chemically so that they can be secreted later for further use by the body. There are two kinds of glands: those that secrete their substances directly into the bloodstream (endocrine glands), and those that secrete their substances through channels or ducts (such as sweat glands and salivary glands).

An aggregation of cells specialized to secrete or excrete materials not related to their ordinary metabolic needs. Glands are divided into two main groups, endocrine and exocrine.
Specific glands will be found under their individual names.

• accessory genital g's — glands other than the gonads, intimately associated with the reproductive organs, especially of the male, in which they include vesicular glands (seminal vesicles), ampullary glands, prostate, bulbourethral glands, coagulating glands. Called also accessory sex glands.
• accessory sex g. — see accessory genital glands (above).
• acinous g. — one made up of one or more oval or spherical sacs (acini).
• alveolar g. — one whose secretory units consist of saclike dilatations with a distinct lumen.
• alveolar–tubular g. — gland composed of a mixture of alveolar and tubular structures.
• ampullary g. — fusiform enlargement of the deferent duct, as it passes across the bladder wall, due to proliferation of glandular tissue in the regionally folded mucosa.
• anal g's — small glands in the anal columnar mucosal cells plus larger and more numerous circumanal glands in the surrounding skin.
• apocrine g. — one whose discharged secretion contains part of the secreting cells.
• avian stomach g's — mucosal and submucosal glands in the stomach of birds; the submucosal glands are thought to secrete both acidic and enzymic substances.
• bronchial g's — glands which contain a mixture of serous and mucus-secreting cells found in the bronchial mucosa.
• buccal g's — buccal salivary glands lying in the submucosal tissues of the cheek and sometimes the orbit and whose ducts secrete directly into the buccal cavity.
• cardiac g. — one of the three (the other two are the pyloric and proper gastric or fundic) types of gland in the stomach wall and capable of secretion into the gastric juices; this gland secretes only mucus.
• carpal g's — cutaneous, ‘marking’ glands found on the medial aspect of the carpus in the pig; although present in both sexes are thought to be used to mark mated females.
• circumoral g's — large glands in the lips of cats; used to mark territory either directly by the familiar fawning head rub, or indirectly by rubbing the secretion of the gland onto the fur during grooming.
• ceruminous g's — cerumin-secreting glands in the skin of the external auditory canal.
• compound g. — one made up of a number of smaller units whose excretory ducts combine to form ducts of progressively higher order.
• deep (lacrimal) g., g. of the third eyelid — an additional lacrimal gland found in the skin of the cartilaginous support of the third eyelid.
• ductless g's — endocrine glands.
• eccrine g. — a gland that secretes its product without loss of cytoplasm, such as the sweat glands on dog footpads or human skin.
• endocrine g's — or ductless glands, discharge their secretions (hormones) directly into the blood; they include the adrenal, pituitary, thyroid and parathyroid glands, the islets of Langerhans in the pancreas, the gonads and the pineal body.
• exocrine g's — discharge through ducts opening on an external or internal surface of the body; include the salivary, sebaceous and sweat glands, the liver, the gastric glands, the pancreas, the intestinal, mammary and lacrimal glands, and the prostate.
• fundic g's, fundus g's — numerous, tubular glands in the mucosa of the stomach that contain the cells which produce acid and pepsin. According to the species, they are usually found in the body and occasionally in the fundus.
• gustatory g. — branched, tubuloalveolar serous glands which open into large lingual papillae.
• hematopoietic g. — glandlike body, e.g. the spleen, that takes a part in blood formation.
• hemolymph g. — small node resembling lymph node but red or brown in color and containing blood sinuses instead of or alongside lymph spaces. Common in ruminants and some rodents and typically located along the large arteries.
• Harderian g. — see harderian gland.
• haversian g. — fold on synovial surface regarded as secretor of synovia.
• holocrine g. — one whose discharged secretion contains the entire secreting cells as in sebaceous glands.
• horn g. — a scent gland found caudomedial to the horn base in goats of both sexes; increase in size and activity in breeding season. Produce the pungent secretion so characteristic of goats, described best as the distilled essence of reek.
• infraorbital g's — special sebaceous glands which line the infraorbital sinus (pouch) in sheep.
• inguinal g's — the collection of special tubular and sebaceous glands which line the inguinal pouch (sinus) in sheep.
• interdigital g's — special sebaceous and tubular glands in the interdigital sinus (pouch) in sheep.
• intestinal g's — microscopic tubular glands which lie in the mucosa of the gut and secrete intestinal juice into the lumen of the small intestine.
• labial g's — minor salivary glands; mucous in small ruminants, serous in others.
• lateral nasal g's — a local glandular thickening of the mucosa lining the maxillary sinus of dogs and some other species; this tissue is largely responsible for the continually wet nose of the dog.
• lingual g. — minor salivary glands, mixed serous and mucous in cattle and horses, mucous in sheep, cats, dogs.
• lymph g's — lymph nodes; they are not glands in the true sense.
• male sex g. — see testis, accessory genital glands (above).
• mammary g. — the milk-secreting organ of female mammals, existing also in a rudimentary state in the male. See also udder, breast.
• mandibular salivary g's — major salivary glands; large and with long salivary ducts to deliver secretion into the mouth.
• marrow-lymph g. — hemolymph gland having a marrow-like tissue.
• meibomian g. — see tarsal gland.
• mental g. — a focal specialization of glands in the skin of the pig, caudal to the mandibular symphysis. It is a round raised nevus-like structure composed of sebaceous and apocrine glands with coarse bristles.
• merocrine g. — one whose discharged secretion contains no part of the secreting cells.
• mixed g's — 1. seromucous glands.
— 2. glands that have both exocrine and endocrine portions.
• molar salivary g. — unique gland in felids; predominantly mucoid cells with a few serous.
• Moll's g's, g's of Moll — see moll's glands.
• multicellular g's — glands which occur as sheets of epithelial cells with secretory function, e.g. gastric and intestinal mucosae.
• multilobular proventricular g's — in the glandular stomach of the bird these glands appear to secrete both pepsin and hydrochloric acid.
• nasal g's — small glands scattered throughout the nasal mucosa.
• nasolabial g. — see nasolabial gland.
• olfactory g's — seromucous glands located beneath the olfactory epithelium; their secretion keeps the local mucosa moist.
• palatine salivary g. — a minor salivary gland containing serous or mucoid or mixed secretory cells.
• palpebral g. — see meibomian gland (above).
• parotid salivary g. — a major salivary gland usually containing serous secretory cells; in carnivores there may also be a few mucus-secreting cells.
• preen g. — see uropygial gland (below).
• preputial g's — sebaceous and apocrine sweat glands within the prepuce; sometimes aggregated into discrete sacs (musk deer) or diverticula (pigs); their secretions combine with desquamated epithelial cells to produce smegma.
• proctodaeal g's — mucous glands containing lymphoid tissue located in the proctodeum of male and female birds.
• proper gastric g. — the main digestive glands of the stomach; found in different parts of the stomach in different species but usually in the body of the stomach; secrete pepsin and hydrochloric acid; open into microscopic pits and clefts.
• scent g. — secrete pheromones which play such a large part in olfactory communication between animals. Located in a variety of places, e.g. in the elephant they are behind the eyes, in the musk deer they are in the belly wall.
• seminal g. — see seminal vesicle.
• sentinel g. — an enlarged lymph node, considered to be pathognomonic of some pathological condition elsewhere.
• sex g's, sexual g's — gonads. See ovary, testis.
• shell g. — the caudal portion of the uterus in the female bird in which the egg is held while the shell is secreted.
• simple g. — one with a nonbranching duct.
• sine ductibus g. — ductless gland.
• solitary g's — solitary follicles.
• sperm host g. — in the vagina of birds; store and nourish visiting spermatozoa which are released when oviposition occurs.
• splenolymph g's — hemolymph glands having more of the splenic type of tissue.
• sublingual salivary g. — a major salivary gland; predominantly mucous cells in ruminants, swine, rodents; mixed serous and mucoid cells in small carnivores and horses.
• submental g's — a group of sebaceous glands in the intermandibular space in cats.
• submucosal intestinal g's — simple, branched, tubuloacinar glands; mucous in ruminants and dogs, mixed serous and mucous in cats and serous in horses and dogs; in carnivores and small ruminants confined to the proximal or middle parts of the duodenum, extend to jejunum in large ruminants, horses, pigs.
• submucosal stomach g. — large, numerous, branched, compound, tubular gland in birds; thought to secrete both acid and enzymatic products.
• sudoriferous g's, sudoriparous g's — sweat glands.
• supracaudal g. — scent producing cells found only in dogs and cats; in dogs confined to a small area at the base of the tail, in cats extend along the dorsal surface of most of the tail; called also tail gland.
• suprarenal g. — see adrenal gland.
• tail g. — see supracaudal gland (above).
• target g. — one specifically affected by a hormone.
• tarsal g. — see meibomian gland (above).
• third eyelid g. — a secondary lacrimal gland; a second, deeper gland occurs in pigs and cattle.
• tubular g. — any gland made up of or containing a tubule or tubules.
• ultimobranchial g. — tissue from the fourth pharyngeal pouch which in mammals is absorbed into the thyroid gland. In fish, amphibians, reptiles and birds the tissue forms separate glands containing calcitonin.
• unicellular g. — a single cell that functions as a gland, e.g. a goblet cell.
• urethral g's — accessory sex glands in males; secrete serous and mucoid liquids into the urethra to nourish and activate spermatozoa.
• uropygial g. — the oil or preen gland of birds is attached to the tail and consists of a bilobed simple tubular, holocrine gland.
• vesicular g. — see seminal vesicle.
• vestibular g's — major and minor mucus-producing glands in the vestibule of the vulva.
• Wolfring g's — small tubuloalveolar glands in subconjunctival tissue above the upper border of the tarsal plate; open onto conjunctiva.
• g's of Zeis, Zeis g's — prominent sebaceous sweat glands on the eyelid margins, associated with hair follicles of cilia. See also external hordeolum.
• Zuckerkandl g. — two large bodies included with the paraganglia along the abdominal aorta.
• zygomatic salivary g. — a unique salivary gland in small carnivores; contains mainly mucous cells with a few serous cells; a modified dorsal buccal gland.

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Dansk (Danish)
1.
n. - kirtel

2.
n. - pakbøsning, pakbrille, manchet

Nederlands (Dutch)
klier, pakkingbus (technisch)

Français (French)
1.
n. - (Anat) glande

2.
n. - (Mécan) presse-étoupe

Deutsch (German)
1.
n. - Drüse

2.
n. - (Tech) Dichtung, Stopfbüchsendeckel

Ελληνική (Greek)
n. - (φυσιολ.) αδένας

Italiano (Italian)
ghiandola, ghianda, premistoppa

Português (Portuguese)
n. - glândula (f) (Anat.), gaxeta (f) de vedação (Téc.)

Русский (Russian)
железа

Español (Spanish)
1.
n. - glándula

2.
n. - artefacto que previene el escape de gases o líquidos

Svenska (Swedish)
n. - körtel (anat.), glandel (bot.)

中文（简体） (Chinese (Simplified))
1. 腺

2. 封函盖

中文（繁體） (Chinese (Traditional))
1.
n. - 封函蓋

2.
n. - 腺

한국어 (Korean)
1.
n. - (신체의 기관에서) ~선

2.
n. - (피스톤의) 패킹 누르개

日本語 (Japanese)
n. - 腺

العربيه (Arabic)
‏(الاسم) غدة‏

עברית (Hebrew)
n. - ‮בלוטה‬
n. - ‮עטיפה של מוט בוכנה‬

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