Exocrine glands are a type of ductal

Duct (anatomy)

In anatomy and physiology, a duct is a circumscribed channel leading from an exocrine gland or organ.-Types of ducts:Examples include:-Duct system:...

 gland

Gland

A gland is an organ in an animal's body that synthesizes a substance for release of substances such as hormones or breast milk, often into the bloodstream or into cavities inside the body or its outer surface .- Types :...

s that secrete their products (including digestive enzymes, and some hormone

Hormone

A hormone is a chemical released by a cell or a gland in one part of the body that sends out messages that affect cells in other parts of the organism. Only a small amount of hormone is required to alter cell metabolism. In essence, it is a chemical messenger that transports a signal from one...

 chemical messengers) into ducts that lead directly into the external environment. They are the counterparts to endocrine glands

Endocrine glands

Endocrine glands are glands of the endocrine system that secrete their products, hormones, directly into the blood rather than through a duct. The main endocrine glands include the pituitary gland, pancreas, ovaries, testes, thyroid gland, and adrenal glands. The hypothalamus is a neuroendocrine...

, which secrete their products (hormones) directly into the blood

Blood

Blood is a specialized bodily fluid in animals that delivers necessary substances such as nutrients and oxygen to the cells and transports metabolic waste products away from those same cells....

stream (ductless glands

Ductless gland

Ductless glands are glands that secrete their product directly onto a surface rather than through a duct. Examples are the goblet cells in the epithelial surface of the digestive, respiratory, urinary and reproductive systems...

) or release hormones (paracrines) that affect only target cells nearby the release site.

Examples

Typical exocrine glands include sweat gland

Sweat gland

Sweat glands, or sudoriferous glands, are small tubular structures of the skin that produce sweat. There are two kinds of sweat glands:...

s, salivary gland

Salivary gland

The salivary glands in mammals are exocrine glands, glands with ducts, that produce saliva. They also secrete amylase, an enzyme that breaks down starch into maltose...

s, mammary gland

Mammary gland

A mammary gland is an organ in mammals that produces milk to feed young offspring. Mammals get their name from the word "mammary". In ruminants such as cows, goats, and deer, the mammary glands are contained in their udders...

s, stomach

Stomach

The stomach is a muscular, hollow, dilated part of the alimentary canal which functions as an important organ of the digestive tract in some animals, including vertebrates, echinoderms, insects , and molluscs. It is involved in the second phase of digestion, following mastication .The stomach is...

, liver

Liver

The liver is a vital organ present in vertebrates and some other animals. It has a wide range of functions, including detoxification, protein synthesis, and production of biochemicals necessary for digestion...

, pancreas

Pancreas

The pancreas is a gland organ in the digestive and endocrine system of vertebrates. It is both an endocrine gland producing several important hormones, including insulin, glucagon, and somatostatin, as well as a digestive organ, secreting pancreatic juice containing digestive enzymes that assist...

. (An example of an endocrine gland is the adrenal gland

Adrenal gland

In mammals, the adrenal glands are endocrine glands that sit atop the kidneys; in humans, the right suprarenal gland is triangular shaped, while the left suprarenal gland is semilunar shaped...

, which is found on top of the kidneys and secretes the hormone adrenaline, among others).

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
  Acinus
  An acinus refers to any cluster of cells that resembles a many-lobed "berry," such as a raspberry...
  
  , or may be a mix of the two (called tubuloacinar). If the glandular portion branches, then the gland is called a branched gland.

Method of secretion

Exocrine glands are named apocrine

Apocrine

Apocrine is a term used to classify exocrine glands in the study of histology. Cells which are classified as apocrine bud their secretions off through the plasma membrane producing membrane-bound vesicles in the lumen. This method is also called decapitation secretion...

 gland, holocrine

Holocrine

Holocrine is a term used to classify the mode of secretion in exocrine glands in the study of histology. Holocrine secretions are produced in the cytoplasm of the cell and released by the rupture of the plasma membrane, which destroys the cell and results in the secretion of the product into the...

 gland, or merocrine

Merocrine

Merocrine is a term used to classify exocrine glands and their secretions in the study of histology. A cell is classified as merocrine if the secretions of that cell are excreted via exocytosis from secretory cells into an epithelial-walled duct or ducts and thence onto a bodily surface or into the...

 gland based on how their product is secreted.

• Apocrine glands - a portion of the plasma membrane buds off the cell, containing the secretion.
• Holocrine glands
  Holocrine glands
  Holocrine glands are a type of secretory gland where the secretory product is formed inside the cytoplasm and the secretion is released by the disruption of the plasma membrane and destruction of the cell. An example is the sebaceous glands of the skin....
  
  - the entire cell disintegrates to secrete its substance, an example is sebaceous glands for skin and nose.
• Merocrine glands - cells secrete their substances by exocytosis
  Exocytosis
  Exocytosis , also known as 'The peni-cytosis', is the durable process by which a cell directs the contents of secretory vesicles out of the cell membrane...
  
   an example is pancreatic acinar cells.

Product secreted

• Serous cells secrete protein
  Protein
  Proteins are biochemical compounds consisting of one or more polypeptides typically folded into a globular or fibrous form, facilitating a biological function. A polypeptide is a single linear polymer chain of amino acids bonded together by peptide bonds between the carboxyl and amino groups of...
  
  s, often enzyme
  Enzyme
  Enzymes are proteins that catalyze chemical reactions. In enzymatic reactions, the molecules at the beginning of the process, called substrates, are converted into different molecules, called products. Almost all chemical reactions in a biological cell need enzymes in order to occur at rates...
  
  s. Examples include chief cell
  Chief cell
  In general, a chief cell is a cell which releases a precursor enzyme. There are two types of chief cells which are most commonly referenced:...
  
  s and Paneth cells
• Mucous cells secrete mucus
  Mucus
  In vertebrates, mucus is a slippery secretion produced by, and covering, mucous membranes. Mucous fluid is typically produced from mucous cells found in mucous glands. Mucous cells secrete products that are rich in glycoproteins and water. Mucous fluid may also originate from mixed glands, which...
  
  . Examples include Brunner's glands
  Brunner's glands
  Brunner's glands are compound tubular submucosal glands found in that portion of the duodenum which is above the hepatopancreatic sphincter...
  
  , esophageal glands
  Esophageal glands
  The esophageal glands are small compound racemose exocrine glands of the mucous type.They are lodged in the submucous tissue, and each opens upon the surface by a long excretory duct....
  
  , and pyloric glands
  Pyloric glands
  The pyloric glands are found in the pyloric portion of the stomach.They consist of two or three short closed tubes opening into a common duct or mouth.These tubes are wavy, and are about one-half the length of the duct....
  
  
• Mixed glands secrete both protein and mucus. Examples include the salivary gland
  Salivary gland
  The salivary glands in mammals are exocrine glands, glands with ducts, that produce saliva. They also secrete amylase, an enzyme that breaks down starch into maltose...
  
  s, although the parotid gland
  Parotid gland
  The paired parotid glands are the largest of the salivary glands. They are each found wrapped around the mandibular ramus, and secrete saliva through Stensen's ducts into the oral cavity, to facilitate mastication and swallowing and to begin the digestion of starches.-Location:The parotid glands...
  
   is predominantly serous, the sublingual gland
  Sublingual gland
  The sublingual glands are salivary glands in the mouth.They lie anterior to the submandibular gland under the tongue, beneath the mucous membrane of the floor of the mouth.They are drained by 8-20 excretory ducts called the ducts of Rivinus....
  
   is predominantly mucous, and the submandibular gland is both serous and mucous.

List of exocrine glands

Glands typically may be referred to by two or more means, though some terms are rarely seen. The names of the anatomists who first described them are often employed, as:

Name(s)	Location	Product	Structure
Apocrine sweat glands Apocrine sweat glands Apocrine sweat glands are sweat glands composed of a coiled secretory portion located at the junction of the dermis and subcutaneous fat, from which a straight portion inserts and secretes into the infundibular portion of the hair follicle...	skin Skin -Dermis:The dermis is the layer of skin beneath the epidermis that consists of connective tissue and cushions the body from stress and strain. The dermis is tightly connected to the epidermis by a basement membrane. It also harbors many Mechanoreceptors that provide the sense of touch and heat...		coiled tubular
Bartholin's glands, Tiedmann's glands, vulvovaginal glands	vulva Vulva The vulva consists of the external genital organs of the female mammal. This article deals with the vulva of the human being, although the structures are similar for other mammals.... , vagina Vagina The vagina is a fibromuscular tubular tract leading from the uterus to the exterior of the body in female placental mammals and marsupials, or to the cloaca in female birds, monotremes, and some reptiles. Female insects and other invertebrates also have a vagina, which is the terminal part of the...
Bauhin's glands Anterior lingual glands Anterior lingual glands are deeply placed seromucous glands that are located near the tip of the tongue on each side of the frenulum linguae. They are found on the under surface of the apex of the tongue, and are covered by a bundle of muscular fibers derived from the Styloglossus and... , anterior lingual glands	tongue Tongue The tongue is a muscular hydrostat on the floors of the mouths of most vertebrates which manipulates food for mastication. It is the primary organ of taste , as much of the upper surface of the tongue is covered in papillae and taste buds. It is sensitive and kept moist by saliva, and is richly... , near tip	nonserous or mixed
Brunner's glands Brunner's glands Brunner's glands are compound tubular submucosal glands found in that portion of the duodenum which is above the hepatopancreatic sphincter... , duodenal glands	duodenum Duodenum The duodenum is the first section of the small intestine in most higher vertebrates, including mammals, reptiles, and birds. In fish, the divisions of the small intestine are not as clear and the terms anterior intestine or proximal intestine may be used instead of duodenum...	mucous	compound tubular
Bulbourethral glands, Cowper's glands, Mery's glands	penis Penis The penis is a biological feature of male animals including both vertebrates and invertebrates... , base	Pre-ejaculate Pre-ejaculate Pre-ejaculate is the clear, colorless, viscous fluid that emits from the urethra of a man's penis when he is sexually aroused. It is similar in composition to semen, but has some significant chemical differences...
Ciaccio's glands Ciaccio's glands Ciaccio's glands are small tubular accessory lacrimal glands found in the lacrimal caruncle of the eyelid. They are located in the upper border of the tarsus, approximately in the middle between the extremities of the tarsal glands. Sometimes they are situated slightly above the tarsus... , accessory lacrimal glands	eye Human eye The human eye is an organ which reacts to light for several purposes. As a conscious sense organ, the eye allows vision. Rod and cone cells in the retina allow conscious light perception and vision including color differentiation and the perception of depth...
Cobelli's glands	esophagus Esophagus The esophagus is an organ in vertebrates which consists of a muscular tube through which food passes from the pharynx to the stomach. During swallowing, food passes from the mouth through the pharynx into the esophagus and travels via peristalsis to the stomach... , just above the cardia Cardia The cardia is the anatomical term for the part of the stomach attached to the esophagus. The cardia begins immediately distal to the z-line of the gastroesophageal junction, where the squamous epithelium of the esophagus gives way to the columnar epithelium of the gastrointestinal tract.Just... , in the mucosa	mucous
Duverney's gland	vagina Vagina The vagina is a fibromuscular tubular tract leading from the uterus to the exterior of the body in female placental mammals and marsupials, or to the cloaca in female birds, monotremes, and some reptiles. Female insects and other invertebrates also have a vagina, which is the terminal part of the... , on either side
Ebner's glands Ebner's glands Ebner's glands are exocrine glands found in the mouth. More specifically, they are serous salivary glands which reside within the moats surrounding the circumvallate papillae in the posterior one-third of the tongue, anterior to the terminal sulcus....	tongue Tongue The tongue is a muscular hydrostat on the floors of the mouths of most vertebrates which manipulates food for mastication. It is the primary organ of taste , as much of the upper surface of the tongue is covered in papillae and taste buds. It is sensitive and kept moist by saliva, and is richly...	serous
Eccrine sweat glands Eccrine sweat glands Eccrine glands are the major sweat glands of the human body, found in virtually all skin.. They produce a clear, odorless substance, consisting primarily of water and NaCl . NaCl is reabsorbed in the duct to reduce salt loss...	skin Skin -Dermis:The dermis is the layer of skin beneath the epidermis that consists of connective tissue and cushions the body from stress and strain. The dermis is tightly connected to the epidermis by a basement membrane. It also harbors many Mechanoreceptors that provide the sense of touch and heat...		coiled tubular
Esophageal glands Esophageal glands The esophageal glands are small compound racemose exocrine glands of the mucous type.They are lodged in the submucous tissue, and each opens upon the surface by a long excretory duct....	esophagus Esophagus The esophagus is an organ in vertebrates which consists of a muscular tube through which food passes from the pharynx to the stomach. During swallowing, food passes from the mouth through the pharynx into the esophagus and travels via peristalsis to the stomach...	mucous	racemose
Exocrine pancreas Exocrine pancreas The exocrine pancreas has ducts that are arranged in clusters called acini . Pancreatic secretions are secreted into the lumen of the acinus, and then accumulate in intralobular ducts that drain to the main pancreatic duct, which drains directly into the duodenum.Control of the exocrine function of...	pancreas Pancreas The pancreas is a gland organ in the digestive and endocrine system of vertebrates. It is both an endocrine gland producing several important hormones, including insulin, glucagon, and somatostatin, as well as a digestive organ, secreting pancreatic juice containing digestive enzymes that assist...	serous	tubulo-acinar
Fränkel's glands	vocal cords, below the edge
Gastric chief cell Gastric chief cell A gastric chief cell is a cell in the stomach that releases pepsinogen, gastric lipase and Chymosin... , Wasmann's glands	stomach Stomach The stomach is a muscular, hollow, dilated part of the alimentary canal which functions as an important organ of the digestive tract in some animals, including vertebrates, echinoderms, insects , and molluscs. It is involved in the second phase of digestion, following mastication .The stomach is...	serous
Glomus coccygeum, coccygeal gland, Luschka's gland or gangliona	coccyx Coccyx The coccyx , commonly referred to as the tailbone, is the final segment of the vertebral column. Comprising three to five separate or fused vertebrae below the sacrum, it is attached to the sacrum by a fibrocartilaginous joint, the sacrococcygeal symphysis, which permits limited movement between... , near the tip
Goblet cells	digestive tract, respiratory tract Respiratory tract In humans the respiratory tract is the part of the anatomy involved with the process of respiration.The respiratory tract is divided into 3 segments:*Upper respiratory tract: nose and nasal passages, paranasal sinuses, and throat or pharynx...	mucous	simple unicellular
Henle's glands Crypts of Henle Crypts of Henle are microscopic pockets found in scattered sections of the conjunctiva around the eyeball. They are responsible for secreting mucin, a proteinous substance that makes up the inner layer of tears. It coats the cornea to provide a hydrophilic layer that allows for even distribution of...	eyelids, in the conjuctiva		tubular
Huguier's glands	vagina Vagina The vagina is a fibromuscular tubular tract leading from the uterus to the exterior of the body in female placental mammals and marsupials, or to the cloaca in female birds, monotremes, and some reptiles. Female insects and other invertebrates also have a vagina, which is the terminal part of the...
Krause's glands Krause's glands Krause's glands are small, mucous accessory lacrimal glands that are found underneath the eyelid where the upper and lower conjuctivae meet. Their ducts unite into a rather long sinus which open into the fornix conjunctiva. There are approximately forty Krause glands in the region of the upper...	conjunctiva Conjunctiva The conjunctiva covers the sclera and lines the inside of the eyelids. It is composed of rare stratified columnar epithelium.-Function:... , middle portion	mucous
Lieberkuhn's glands	intestines, surface of mucous membrane Mucous membrane The mucous membranes are linings of mostly endodermal origin, covered in epithelium, which are involved in absorption and secretion. They line cavities that are exposed to the external environment and internal organs...		simple tubular
Littré's glands, Morgagni's glands	spongy portion of the urethra		racemose
Mammary gland Mammary gland A mammary gland is an organ in mammals that produces milk to feed young offspring. Mammals get their name from the word "mammary". In ruminants such as cows, goats, and deer, the mammary glands are contained in their udders...	breast Breast The breast is the upper ventral region of the torso of a primate, in left and right sides, which in a female contains the mammary gland that secretes milk used to feed infants.Both men and women develop breasts from the same embryological tissues...		compound tubulo-acinar
Meibomian gland Meibomian gland The meibomian glands are a special kind of sebaceous gland at the rim of the eyelids inside the tarsal plate, responsible for the supply of meibum, an oily substance that prevents evaporation of the eye's tear film. They prevent tear spillage onto the cheek, trapping tears between the oiled edge...	eyelids	sebaceous
Moll's glands Glands of Moll Glands of Moll, also known as ciliary glands, are modified apocrine sweat glands that are found on the margin of the eyelid. They are next to the base of the eyelashes, and anterior to the Meibomian glands within the distal eyelid margin. These glands are relatively large and tubular-shaped.Moll's...	eyelids
Montgomery's glands	mammary areola Areola This article is about the breast tissue. For the entomology term, see the glossary of Lepidopteran terms. For an artistic cloud motif, see aureola. For the cactus feature, see Areole....	sebaceous
Naboth's glands	cervix Cervix The cervix is the lower, narrow portion of the uterus where it joins with the top end of the vagina. It is cylindrical or conical in shape and protrudes through the upper anterior vaginal wall...  and os uteri	mucous
Olfactory glands Olfactory glands Bowman's glands are situated in the olfactory mucosa, beneath the olfactory epithelium, in the lamina propria, a connective tissue also containing fibroblasts, blood vessels, and bundles of fine axons from the olfactory neurons.The structure of the Bowman's glands consists of an acinus in the... , Bowman's glands	nose Human nose The visible part of the human nose is the protruding part of the face that bears the nostrils. The shape of the nose is determined by the ethmoid bone and the nasal septum, which consists mostly of cartilage and which separates the nostrils... , olfactory region
Paneth cells Paneth cells Paneth cells, along with goblet cells, enterocytes, and enteroendocrine cells, represent the principal cell types of the epithelium of the small intestine...	small intestine Small intestine The small intestine is the part of the gastrointestinal tract following the stomach and followed by the large intestine, and is where much of the digestion and absorption of food takes place. In invertebrates such as worms, the terms "gastrointestinal tract" and "large intestine" are often used to...	serous
Gley's glands, Sandstroem's glands
parotid gland Parotid gland The paired parotid glands are the largest of the salivary glands. They are each found wrapped around the mandibular ramus, and secrete saliva through Stensen's ducts into the oral cavity, to facilitate mastication and swallowing and to begin the digestion of starches.-Location:The parotid glands...	mouth Mouth The mouth is the first portion of the alimentary canal that receives food andsaliva. The oral mucosa is the mucous membrane epithelium lining the inside of the mouth....	serous	tubulo-alveolar
Peyer's patches (or glands)	ileum Ileum The ileum is the final section of the small intestine in most higher vertebrates, including mammals, reptiles, and birds. In fish, the divisions of the small intestine are not as clear and the terms posterior intestine or distal intestine may be used instead of ileum.The ileum follows the duodenum... , lymphatic glands
Prostate Prostate The prostate is a compound tubuloalveolar exocrine gland of the male reproductive system in most mammals....	surrounds the urethra Urethra In anatomy, the urethra is a tube that connects the urinary bladder to the genitals for the removal of fluids out of the body. In males, the urethra travels through the penis, and carries semen as well as urine...  just below the urinary bladder Urinary bladder The urinary bladder is the organ that collects urine excreted by the kidneys before disposal by urination. A hollow muscular, and distensible organ, the bladder sits on the pelvic floor...
Pyloric glands Pyloric glands The pyloric glands are found in the pyloric portion of the stomach.They consist of two or three short closed tubes opening into a common duct or mouth.These tubes are wavy, and are about one-half the length of the duct....	stomach Stomach The stomach is a muscular, hollow, dilated part of the alimentary canal which functions as an important organ of the digestive tract in some animals, including vertebrates, echinoderms, insects , and molluscs. It is involved in the second phase of digestion, following mastication .The stomach is...	mucous	simple branched tubular
Sebaceous gland Sebaceous gland The sebaceous glands are microscopic glands in the skin that secrete an oily/waxy matter, called sebum, to lubricate and waterproof the skin and hair of mammals...	skin Skin -Dermis:The dermis is the layer of skin beneath the epidermis that consists of connective tissue and cushions the body from stress and strain. The dermis is tightly connected to the epidermis by a basement membrane. It also harbors many Mechanoreceptors that provide the sense of touch and heat...	sebum	acinar - branched
Skene's glands, Guérin's glands	vagina Vagina The vagina is a fibromuscular tubular tract leading from the uterus to the exterior of the body in female placental mammals and marsupials, or to the cloaca in female birds, monotremes, and some reptiles. Female insects and other invertebrates also have a vagina, which is the terminal part of the...
Sublingual gland Sublingual gland The sublingual glands are salivary glands in the mouth.They lie anterior to the submandibular gland under the tongue, beneath the mucous membrane of the floor of the mouth.They are drained by 8-20 excretory ducts called the ducts of Rivinus.... , Rivini's gland	mouth Mouth The mouth is the first portion of the alimentary canal that receives food andsaliva. The oral mucosa is the mucous membrane epithelium lining the inside of the mouth....	mucus (primarily)	tubulo-alveolar
Submandibular gland Submandibular gland The paired submandibular glands are salivary glands located beneath the floor of the mouth. In humans, they account for 70% of the salivary volume and weigh about 15 grams. Unstimulated in humans, the percentage contribution to whole saliva; ~25% Parotid, Submandibular and Sublingual ~ 67% and...	mouth Mouth The mouth is the first portion of the alimentary canal that receives food andsaliva. The oral mucosa is the mucous membrane epithelium lining the inside of the mouth....	mixed (M+S)	tubulo-alveolar
Sudoriparous glands, Boerhaave's glands	skin Skin -Dermis:The dermis is the layer of skin beneath the epidermis that consists of connective tissue and cushions the body from stress and strain. The dermis is tightly connected to the epidermis by a basement membrane. It also harbors many Mechanoreceptors that provide the sense of touch and heat...
Sigmund's glands	epitrochlear lymph node Lymph node A lymph node is a small ball or an oval-shaped organ of the immune system, distributed widely throughout the body including the armpit and stomach/gut and linked by lymphatic vessels. Lymph nodes are garrisons of B, T, and other immune cells. Lymph nodes are found all through the body, and act as... s
Suzanne's gland	mouth, beneath the alveolingual groove	mucous
Weber's glands	tongue Tongue The tongue is a muscular hydrostat on the floors of the mouths of most vertebrates which manipulates food for mastication. It is the primary organ of taste , as much of the upper surface of the tongue is covered in papillae and taste buds. It is sensitive and kept moist by saliva, and is richly...	mucous	tubular
Glands of Zeis Glands of Zeis Glands of Zeis are unilobar sebaceous glands located on the margin of the eyelid. The glands of Zeis service the eyelash. These glands produce an oily substance that is issued through the excretory ducts of the sebaceous lobule into the middle portion of the hair follicle...	eyelids, free edges	sebaceous

External links

• Diagram at mhhe.com