Exocrine glands

Exocrine gland
Latin glandula exocrina
Code Template:TerminologiaHistologica

In the animal kingdom, the general term gland falls into two major categories with further subtypes falling under each of these.

An Exocrine gland is distinguished by the fact that it excretes its essential product by way of a duct to some environment external to itself, be it either inside the body or on a surface of the body.

Examples of exocrine glands include the sweat glands, salivary glands, mammary glands, pancreas and liver.

An Endocrine gland is its counterpart. It secretes its essential product without the use of a duct directly into the bloodstream or else by diffusion into its surrounding tissue (paracrine signaling) where it often affects only target cells near the release site.

Examples of endocrine glands include the adrenal glands, located atop the kidneys and responsible for the secretion of certain hormones such as adrenaline, cortisol and others. The testes, in males and ovaries in females are not only gonads, organs which generate male and female germ cells respectively, but are also endocrine glands in that they produce various androgens and estrogens together known as steroidal sex hormones.

Further classification of exocrine glands

By structure

Exocrine glands contain a glandular portion and a duct portion, the structures of which can be used to classify the gland.

  • The duct portion may be branched (called compound) or unbranched (called simple).
  • The glandular portion may be tubular or acinar, or may be a mix of the two (called tubuloacinar). If the glandular portion branches, then the gland is called a branched gland.

By method of excretion

Exocrine glands are named apocrine glands, holocrine glands, or merocrine glands based on how their products are excreted.

  • Merocrine glands or (eccrine glands) - cells excrete their substances by exocytosis; for example, pancreatic acinar cells.
  • Apocrine glands - a portion of the plasma membrane buds off the cell, containing the excretion.
  • Holocrine glands - the entire cell disintegrates to excrete its substance; for example, sebaceous glands of the skin and nose.

By product excreted

  • Serous cells excrete proteins, often enzymes. Examples include chief cells and Paneth cells
  • Mucous cells excrete mucus. Examples include Brunner's glands, esophageal glands, and pyloric glands
  • Mixed glands excrete both protein and mucus. Examples include the salivary glands, although the parotid gland is predominantly serous, the sublingual gland is predominantly mucous, and the submandibular gland is both serous and mucous.

List of exocrine glands

Name(s) Location Product Structure
Apocrine sweat glands skin coiled tubular
Bartholin's glands, Tiedmann's glands, vulvovaginal glands vulva, vagina
Bauhin's glands, anterior lingual glands tongue, near tip nonserous or mixed
Brunner's glands, duodenum mucous compound tubular
Bulbourethral glands, Cowper's glands, Mery's glands penis, base Pre-ejaculate
Ciaccio's glands, accessory lacrimal glands eye
Cobelli's glands esophagus, just above the cardia, in the mucosa mucous
Ebner's glands tongue serous
Eccrine sweat glands skin coiled tubular
Esophageal glands esophagus mucous racemose
Exocrine pancreas pancreas serous tubulo-acinar
Fränkel's glands vocal cords, below the edge
Gastric chief cell, Wasmann's glands stomach serous
Glomus coccygeum, coccygeal gland, Luschka's gland or gangliona coccyx, near the tip
Goblet cells digestive tract, respiratory tract mucous simple unicellular
Henle's glands eyelids, in the conjuctiva tubular
Krause's glands conjunctiva, middle portion mucous
Lieberkuhn's glands intestines, surface of mucous membrane simple tubular
Littré's glands, Morgagni's glands spongy portion of the urethra racemose
Mammary gland breast compound tubulo-acinar
Meibomian gland eyelids sebaceous
Moll's glands eyelids
Montgomery's glands mammary areola sebaceous
Naboth's glands cervix and os uteri mucous
Olfactory glands, Bowman's glands nose, olfactory region
Paneth cells small intestine serous
Gley's glands, Sandstroem's glands
parotid gland mouth serous tubulo-alveolar
Peyer's patches (or glands) ileum, lymphatic glands
Prostate surrounds the urethra just below the urinary bladder
Pyloric glands stomach mucous simple branched tubular
Sebaceous gland skin sebum acinar - branched
Skene's glands, Guérin's glands vagina
Sublingual gland, Rivini's gland mouth mucus (primarily) tubulo-alveolar
Submandibular gland mouth mixed (M+S) tubulo-alveolar
Sudoriparous glands, Boerhaave's glands skin
Sigmund's glands epitrochlear lymph nodes
Suzanne's gland mouth, beneath the alveolingual groove mucous
Weber's glands tongue mucous tubular
Glands of Zeis eyelids, free edges sebaceous

See also

Additional images

External links

  • Diagram at mhhe.com
  • eMedicine Dictionary
  1. REDIRECT Template:Epithelium and epithelial tissue
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