Glands

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

Types of gland
Humans have a large variety of glands, from the pituitary gland in the brain, to sweat glands over the body's skin that release perspiration to regulate the body's temperature. Other well known glands include the adrenal glands, the prostate gland, the thyroid gland, the pineal gland, the thymus and mammary gland. Two other paired glands are the parotid glands and submandibular glands, both involved in saliva production.

Formation
Every gland is formed by an ingrowth from an epithelial surface. This ingrowth may from the beginning possess 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, simple tubular if there is no division (large intestine), compound tubular if branching occurs (pyloric glands of stomach). In the simple tubular glands the gland may be coiled without losing its tubular form, e.g. in sweat glands.

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. They are again subdivided into simple or compound alveolar glands, as in the case of the tubular glands. A further complication in the case of the alveolar glands may occur in the form of still smaller saccular diverticuli growing out from the main sacculi. These are termed alveoli.

Naming
Glands typically may be referred to by two or more means, though some terms are rarely seen. The names of men are often employed, as:
 * Bartholin's glands - Tiedmann's glands. The vulvovaginal glands.
 * Baughin's glands - nonserous or mixed glands near the tip of the tongue. The anterior lingual glands.
 * Boerhaave's glands - the sudoriparous glands.
 * Bowman's glands - glands in the olfactory region of the nose.
 * Ciaccio's glands - the accessory lacrimal glands.
 * Cobelli's glands - mucous glands in the mucosa of the esophagus just above the cardia.
 * Cowper's glands - bulbourethral glands. Also called Mery's glands.
 * Duverney's gland - a minute gland on either side of the vagina.
 * Ebner's glands - mucous glands of the tongue.
 * Fr&auml;nkel's glands - minute glands that open below the edge of the vocal cords.
 * Gley's glands - the parathyroid glands. Also called Sandstroem's glands.
 * Gu&eacute;rin's glands - Skene's glands.
 * Henle's glands - tubular glands in the conjuctiva of the eyelids.
 * Huguier's glands - two minor vaginal glands.
 * Krause's glands - mucous glands of the middle portion of the conjunctiva.
 * Lieberkuhn's glands - simple tubular glands opening on the surface of the intestinal mucous membrane.
 * Littr&eacute;'s glands - racemose glands in the spongy portion of the urethra. Also called Morgagni's glands.
 * Luschka's gland or ganglion - coccygeal gland or glomus coccygeum, a small  vascular organ near the tip of the coccyx.
 * Moll's glands - certain small glands of the eyelids.
 * Montgomery's glands - sebaceous glands of the mammary areola.
 * Naboth's glands - distended mucous glands within the cervix and about the os uteri.
 * Peyer's glands - lymphatic glands, chiefly of the ileum.
 * Rivini's gland - the sublingual gland.
 * Sigmund's glands - the epitrochlear lymph nodes.
 * Suzanne's gland - a mucous gland of the mouth, beneath the alveolingual groove.
 * Wasmann's glands - the peptic glands.
 * Weber's glands - the tubular mucous glands of the tongue.
 * Glands of Zeis - sebaceous glands on the free edges of the eyelids. Named for Edward Zeis (1807-68), opthalmologist at Dresden.