mammary gland

n. Any of the milk-producing glands in female mammals, consisting of lobes containing clusters of alveoli with a system of ducts to convey the milk to an external nipple or teat. These glands typically occur in pairs and begin secreting milk when young are born.

mammary gland

n 1. (Anatomy) any of the milk-producing glands in mammals. In higher mammals each gland consists of a network of tubes and cavities connected to the exterior by a nipple 2. (Zoology) any of the milk-producing glands in mammals. In higher mammals each gland consists of a network of tubes and cavities connected to the exterior by a nipple

mam′mary gland`

n. any of the accessory reproductive organs of female mammals that occur in pairs on the chest or ventral surface and contain milk-producing lobes with ducts that empty into a nipple.

mam·ma·ry gland

(măm′ə-rē) One of the glands in female mammals that produces milk. It is present but undeveloped in the male. In most animals, the gland opens onto the surface by means of a nipple or teat.

Thesaurus

Noun

mammary gland - milk-secreting organ of female mammalsmammafemale mammal - animals that nourish their young with milkdug - an udder or breast or teatudder, bag - mammary gland of bovids (cows and sheep and goats)duct gland, exocrine, exocrine gland - a gland that secretes externally through a ducttit, titty, boob, breast, knocker, bosom - either of two soft fleshy milk-secreting glandular organs on the chest of a womanmamilla, mammilla, nipple, teat, tit, pap - the small projection of a mammary gland

Translations

mammary gland

mammary gland,

organ of the female mammal that produces and secretes milk for the nourishment of the young. A mammal may have from 1 to 11 pairs of mammary glands, depending on the species. Generally, those mammals that bear larger litters have more glands. The mammary gland of the cow and of some other mammals is known as the udder.

In humans, there is one pair of mammary glands, also known as mammae, or breasts. They are rudimentary in both sexes until the age of puberty when, in response to ovarian hormones, they begin to develop in the female. During pregnancy, they distend still further in preparation for nursing the infant. Pregnant women are prevented from lactating (producing milk) by the presence in the blood of high levels of estrogenestrogen
, any one of a group of hormones synthesized by the reproductive organs and adrenal glands in females and, in lesser quantities, in males. The estrogens cause the thickening of the lining of the uterus and vagina in the early phase of the ovulatory, or menstrual, cycle
..... Click the link for more information. and progesteroneprogesterone
, female sex hormone that induces secretory changes in the lining of the uterus essential for successful implantation of a fertilized egg. A steroid, progesterone is secreted chiefly by the corpus luteum, a group of cells formed in the ovary after the follicle
..... Click the link for more information. , secreted by the placenta until birth occurs.

After birth, response to prolactin, the milk-stimulating hormone, is no longer inhibited by placental hormones, and lactation begins. Mammary tissue contains between 15 and 20 compartments called lobes, each of which is divided into smaller compartments called lobules. The lobes and lobules are connected by a network of tubes whose cells manufacture the liquid and fatty substances that form milk. The tubes of each lobe connect with a duct, and all ducts lead to the nipple, where the milk is secreted when the nipple is sucked by the young. The letdown of milk during the nursing process is aided by oxytocinoxytocin
, hormone released from the posterior lobe of the pituitary gland that facilitates uterine contractions and the milk-ejection reflex. The structure of oxytocin, a cyclic peptide consisting of nine amino acids, was determined in 1953 and in the same year it was
..... Click the link for more information. , a hormone secreted by the pituitary. The physical force of an infant's sucking on the breast is a major stimulus to milk production. Disorders of the mammary gland include mastitismastitis
, inflammation of the breast. Mastitis most commonly occurs in nursing mothers between the first and third weeks after childbirth, usually of the first child. It is an infection that results when bacteria enter through cracked nipples; the organisms may already be in
..... Click the link for more information. and breast cancerbreast cancer,
cancer that originates in the breast. Breast cancer is the second leading cause of cancer death in women (following lung cancer). Although the vast majority of the cases occur in women, some men also get breast cancer.
..... Click the link for more information. .

Mammary gland

A unique anatomical structure of mammals that secretes milk for the nourishment of the newborn. The mammary gland contains thousands of milk-producing units called alveoli, each of which consists of a unicellular layer of epithelial cells arranged in a spheroid structure. The alveolar epithelial cells take up a variety of nutrients from the blood that perfuses the outer surface of the alveolar structures. Some of the nutrients are then secreted directly into the alveolar lumen; other nutrients are used to synthesize the unique constituents of milk which are then secreted. Each alveolus is connected to a duct through which milk flows. The ducts from many alveoli are connected via a converging ductal system which opens externally by way of the lactiferous pore.

Surrounding each alveolus and its associated small ducts are smooth muscle cells called myoepithelial cells. These cells contract in response to the posterior pituitary hormone oxytocin; milk is thus forced out of the alveoli, through the ductal system, and out the lactiferous pore for the nourishment of the newborn. The release of oxytocin is a neuroendocrine reflex triggered by the stimulation of sensory receptors by the suckling of the newborn. See Endocrine mechanisms

Mammary glands are basically highly modified and specialized sebaceous glands which derive from ectoderm. In the embryo, mammary lines, formed on both sides of the midventral line, mark the location of future mammary glands. Along the mammary lines discrete ectodermal ingrowths, called mammary buds, produce a rudimentary branched system of ducts at birth. In all species (except the monotremes) a nipple or teat develops in concert with the mammary buds. In the most primitive mammal (the duckbill or platypus), which lacks nipples or teats, milk simply oozes out of the two mammary gland areas and is lapped up by the young.

From birth to sexual maturity the mammary gland consists of a nipple and a rudimentary ductal system in both males and females. At the onset of puberty in the female, the enhanced secretion of estrogen causes a further development of the mammary ductal system and an accumulation of lipids in fat cells. After puberty in women, the mammary gland consists of about 85% fat cells and a partially developed ductal system. See Estrogen

During pregnancy the mammary gland comes under the influence of estrogen and progesterone which are derived from both the ovary and placenta. These hormones cause a further branching of the ductal system and the development of milk-secreting structures, the alveoli. In humans, approximately 200 alveoli are surrounded by a connective tissue sheath forming a structure called a lobule. About 26 lobules are packaged via another connective tissue sheath into a larger structure called a lobe. Each of 15–20 lobes is exteriorized into the nipple via separate lactiferous pores. See Progesterone

A complement of hormones maximizes the development of the ductal and lobuloalveolar elements in the mammary gland. Optimal ductal growth is attained with estrogen, a glucocorticoid, prolactin, and insulin. Maximal lobuloalveolar growth is obtained with estrogen, progesterone, growth hormone, prolactin, a glucocorticoid, and insulin. During pregnancy estrogen and progesterone stimulate mammary development but inhibit milk production.

During the final third of pregnancy, the alveolar epithelial cells begin secreting a fluid called colostrum. This fluid fills the alveoli and causes a gradual enlargement of the breast or udder. At parturition, the inhibitory influence of estrogen and progesterone is removed, and the gland can secrete milk under the influence of a further complement of hormones including prolactin, a glucocorticoid, insulin, and the thyroid hormones. See Gland, Lactation, Mammalia, Milk, Pregnancy

mammary gland

[′mam·ə·rē ‚gland] (physiology) A highly modified sebaceous gland that secretes milk; a unique anatomical feature of mammals.

mammary gland

any of the milk-producing glands in mammals. In higher mammals each gland consists of a network of tubes and cavities connected to the exterior by a nipple

mammary gland

gland

[gland] 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. adj., adj glan´dular.
The endocrine glands, or ductless glands, discharge their secretions (hormones) directly into the blood; they include the adrenal, pituitary, thyroid, and parathyroid glands, the islands of Langerhans in the pancreas, the gonads, the thymus, and the pineal body. The glands" >exocrine glands discharge through ducts opening on an external or internal surface of the body; they include the salivary, sebaceous, and sweat glands, the liver, the gastric glands, the pancreas, the intestinal, mammary, and lacrimal glands, and the prostate. The lymph nodes" >lymph nodes are sometimes called lymph glands but are not glands in the usual sense.

Classification of glands according to mode of secretion. From Applegate, 2000.acinous gland one made up of one or more acini" >acini (oval or spherical sacs).adrenal gland see adrenal gland.apocrine gland one whose discharged secretion contains part of the secreting cells.areolar g's Montgomery's glands.axillary g's lymph nodes in the axilla.Bartholin g's two small mucus-secreting glands, one on each side in the lower pole of the labium majus and connected to the surface by a duct lined with transitional cells, which opens just external to the hymenal ring. Their exact function is not clear but they are believed to secrete mucus to moisten the vestibule during sexual excitement. Called also major vestibular glands.Bowman's g's olfactory glands.bronchial g's seromucous glands in the mucosa and submucosa of the bronchial walls.Brunner's g's glands in the submucosa of the duodenum that secrete intestinal juice; called also duodenal glands.buccal g's seromucous glands on the inner surface of the cheeks; called also genal glands.bulbocavernous g's (bulbourethral g's) two glands embedded in the substance of the sphincter of the male urethra, posterior to the membranous part of the urethra; their secretion lubricates the urethra; called also Cowper's glands.cardiac g's mucus-secreting glands of the cardiac part (cardia) of the stomach.celiac g's lymph nodes anterior to the abdominal aorta.ceruminous g's cerumin-secreting glands in the skin of the external auditory canal.cervical g's 1. the lymph nodes of the neck.2. compound clefts in the wall of the uterine cervix.ciliary g's sweat glands that have become arrested in their development, situated at the edges of the eyelids; called also Moll's glands.circumanal g's specialized sweat and sebaceous glands around the anus; called also Gay's glands.Cobelli's g's mucous glands in the esophageal mucosa just above the cardia.coccygeal gland glomus coccygeum.compound gland one made up of a number of smaller units whose excretory ducts combine to form ducts of progressively higher order.Cowper's g's bulbourethral glands.ductless g's endocrine glands.duodenal g's Brunner's glands.Ebner's g's serous glands at the back of the tongue near the taste buds.eccrine gland one of the ordinary or simple sweat glands, which are of the merocrine type.endocrine g's see endocrine glands.exocrine g's glands that discharge their secretions through ducts opening on internal or external surfaces of the body; see gland" >gland.fundic g's (fundus g's) numerous tubular glands in the mucosa of the fundus and body of the stomach that contain the cells that produce acid and pepsin.gastric g's the secreting glands of the stomach, including the fundic, cardiac, and pyloric glands.Gay's g's circumanal glands.genal g's buccal glands.glossopalatine g's mucous glands at the posterior end of the smaller sublingual glands.haversian g's synovial villi.holocrine gland one whose discharged secretion contains the entire secreting cells.intestinal g's straight tubular glands in the mucous membrane of the intestines, in the small intestine opening between the bases of the villi, and containing argentaffin cells. Called also crypts or glands of Lieberkühn.jugular gland a lymph node behind the clavicular insertion of the sternocleidomastoid muscle.Krause's gland an accessory lacrimal gland deep in the conjunctival connective tissue, mainly near the upper fornix.lacrimal g's the glands that secrete tears; see also lacrimal apparatus.g's of Lieberkühn intestinal glands.lingual g's the seromucous glands on the surface of the tongue.lingual g's, anterior seromucous glands near the apex of the tongue.Littre's g's 1. preputial glands.2. the male urethral glands.lymph gland lymph node.major vestibular g's Bartholin glands.mammary gland a specialized gland of the skin of female mammals, which secretes milk for the nourishment of their young; it exists in a rudimentary state in the male. See also breast.meibomian g's sebaceous follicles between the cartilage and conjunctiva of the eyelids. Called also tarsal glands.merocrine gland 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.Moll's g's ciliary glands.Montgomery's g's sebaceous glands in the mammary areola; called also areolar glands.mucous g's glands that secrete mucus.olfactory g's small mucous glands in the olfactory mucosa; called also Bowman's glands.parathyroid g's see parathyroid glands.parotid g's see parotid glands.peptic g's gastric glands that secrete pepsin.pineal gland pineal body.pituitary gland see pituitary gland.preputial g's small sebaceous glands of the corona of the penis and the inner surface of the prepuce, which secrete smegma; called also Littre's glands and Tyson's glands.prostate gland prostate.pyloric g's the mucin-secreting glands of the pyloric part of the stomach.salivary g's see salivary glands.sebaceous gland a type of holocrine gland of the corium that secretes an oily material (sebum) into the hair follicles.

Glands: The relationship of the hair follicle, eccrine and apocrine sweat glands and sebaceous glands. From Copstead, 1995.sentinel gland an enlarged lymph node, considered to be pathognomonic of some pathologic condition elsewhere.seromucous g's glands that are both serous and mucous.serous gland a gland that secretes a watery albuminous material, commonly but not always containing enzymes.sex gland (sexual gland) gonad.simple gland one with a nonbranching duct.Skene's g's the largest of the female urethral glands, which open into the urethral orifice; they are regarded as homologous with the prostate. Called also paraurethral ducts.solitary g's solitary follicles.sublingual gland a salivary gland on either side under the tongue.submandibular gland (submaxillary gland) a salivary gland on the inner side of each ramus of the mandible.sudoriferous gland (sudoriparous gland) sweat gland.suprarenal gland adrenal gland.sweat gland see sweat gland.target gland any gland affected by a secretion or other stimulus from another gland, such as those affected by the secretions of the pituitary gland.tarsal g's meibomian glands.thymus gland thymus.thyroid gland see thyroid gland.tubular gland any gland made up of or containing a tubule or tubules.Tyson's g's preputial glands.unicellular gland a single cell that functions as a gland, e.g., a goblet cell.urethral g's mucous glands in the wall of the urethra; in the male, called also Littre's glands.uterine g's simple tubular glands found throughout the thickness and extent of the endometrium; they become enlarged during the premenstrual period.vesical g's mucous glands sometimes found in the wall of the urinary bladder, especially in the area of the trigone.vulvovaginal g's Bartholin's glands.Waldeyer's g's glands in the attached edge of the eyelid.Weber's g's the tubular mucous glands of the tongue.

mam·ma·ry gland

[TA] the potential and active compound, alveolar, mostly merocrine (with possible apocrine components) milk-secreting gland lying within the breast; it comprises 15-24 lobes, each consisting of many lobules, separated by adipose tissue and fibrous septa; the parenchyma of the resting postpubertal female gland consists of ducts; the alveoli develop only during pregnancy and remain active until weaning; normally, the gland remains rudimentary (undistinguishable from its childhood state) in men.
See also: breast (2). Synonym(s): glandula mammaria [TA], lactiferous gland, milk gland

mammary gland

The gland of the mammalian female breast which is responsible for lactation (production and transportation of milk) to the nipples via the mammary ducts.

mam·ma·ry gland

(măm'ă-rē gland) [TA] The compound alveolar apocrine secretory gland that forms the breast. It consists of 15-24 lobes, each consisting of many lobules, separated by adipose tissue and fibrous septa; the parenchyma of the resting gland consists of ducts; the alveoli develop only during pregnancy.
Synonym(s): lactiferous glands.

mammary gland

The breast. This is rudimentary in the male but developed and capable of the function of long-term milk production in the female. The word mamma is both Greek and Latin for breast and may derive originally from the sound made by hungry babies. See also BREAST ABSCESS, BREAST CANCER, BREAST ENLARGEMENT and BREAST-FEEDING.

mammary gland

milk gland

a gland present in female MAMMALS that produces milk used to suckle their young (see LACTATION). It probably evolved from a modified sweat gland and at least two are normally present, though in many mammals which produce large numbers of offspring more than two are developed, usually concentrated on the underbelly beneath the pelvic girdle. In most mammals the size of the gland is determined by the state of the OESTROUS CYCLE.

mammary gland

mammary gland

mammary gland

mam′mary gland`

mam·ma·ry gland

mammary gland

mammary gland,

Mammary gland

mammary gland

mammary gland

mammary gland

gland

mam·ma·ry gland

mammary gland

mammary gland

mam·ma·ry gland

mammary gland

mammary gland

milk gland

mammary gland

Synonyms for mammary gland

noun milk-secreting organ of female mammals

Synonyms

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