Brunner's glands (or duodenal glands) are compound tubuloalveolar
submucosal
gland
A gland is a Cell (biology), cell or an Organ (biology), organ in an animal's body that produces and secretes different substances that the organism needs, either into the bloodstream or into a body cavity or outer surface. A gland may also funct ...
s found in that portion of the
duodenum
The duodenum is the first section of the small intestine in most vertebrates, including mammals, reptiles, and birds. In mammals, it may be the principal site for iron absorption.
The duodenum precedes the jejunum and ileum and is the shortest p ...
proximal to the
hepatopancreatic sphincter (i.e sphincter of Oddi).
For decades, it was believed that the main function of the glands is to secrete alkaline (
bicarbonate
In inorganic chemistry, bicarbonate (IUPAC-recommended nomenclature: hydrogencarbonate) is an intermediate form in the deprotonation of carbonic acid. It is a polyatomic anion with the chemical formula .
Bicarbonate serves a crucial bioche ...
-containing) mucus in order to:
* protect the duodenum from the acidic content of
chyme
Chyme or chymus (; ) is the semi-fluid mass of partly digested food that is expelled by the stomach, through the pyloric valve, into the duodenum (the beginning of the small intestine).
Chyme results from the mechanical and chemical breakdown ...
(which enters the duodenum from the
stomach
The stomach is a muscular, hollow organ in the upper gastrointestinal tract of Human, humans and many other animals, including several invertebrates. The Ancient Greek name for the stomach is ''gaster'' which is used as ''gastric'' in medical t ...
),
* provide an alkaline environment which promotes the activity of intestinal enzymes,
* lubricate the intestinal walls.
However, more recent studies have demonstrated that Brunner’s glands actually act as major modulators of the gut microbiome and systemic immunity.
They are the distinguishing feature of the duodenum, and are named for the
Swiss
Swiss most commonly refers to:
* the adjectival form of Switzerland
* Swiss people
Swiss may also refer to: Places
* Swiss, Missouri
* Swiss, North Carolina
* Swiss, West Virginia
* Swiss, Wisconsin
Other uses
* Swiss Café, an old café located ...
physician who first described them,
Johann Conrad Brunner.
Structure
Duodenal glands are situated within the mucosa and submucosa of the duodenum. They are most abundant near the pylorus, growing shorter and more sparse distally towards the terminal portion of the duodenum.
The duodenum can be distinguished from the
jejunum
The jejunum is the second part of the small intestine in humans and most higher vertebrates, including mammals, reptiles, and birds. Its lining is specialized for the absorption by enterocytes of small nutrient molecules which have been pr ...
and
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 ...
by the presence of Brunner's glands in the submucosa.
Histology
Their excretory cannals are tortuous, opening at the bases of the villi.
Two forms of duodenal glands are distinguished: the external group (which are more voluminous and extend into the duodenal submucosa), and the internal group (which are smaller and are situated within the duodenal mucosa).
Function
They also secrete
epidermal growth factor, which inhibits
parietal and
chief cells of the stomach from secreting acid and their digestive enzymes. This is another form of protection for the duodenum.
The Brunner glands, which empty into the
intestinal glands, secrete an alkaline fluid composed of
mucin
Mucins () are a family of high molecular weight, heavily glycosylated proteins ( glycoconjugates) produced by epithelial tissues in most animals. Mucins' key characteristic is their ability to form gels; therefore they are a key component in ...
, which exerts a physiologic anti-acid function by coating the duodenal epithelium, therefore protecting it from the acid chyme of the stomach. Furthermore, in response to the presence of acid in the duodenum, these glands secrete
pepsinogen and
urogastrone, which inhibit gastric acid secretion.
More recent studies have demonstrated that Brunner’s glands are major modulators of the gut microbiome and systemic immunity. Studies conducted by
Ivan De Araujo’s laboratory revealed that Brunner’s gland secretions promote the proliferation of probiotics and protect the host against foreign pathogens.
[ ]
Clinical significance
Hyperplasia of Brunner glands with a lesion greater than 1 cm was initially described as a Brunner gland adenoma. Several features of these lesions favor their designation as
hamartomas, including the lack of encapsulation; the mixture of acini, smooth muscles, adipose tissue, Paneth cells, and mucosal glands; and the lack of any cell atypia. These hamartomas are rare, with approximately 150 cases described in the literature. It is estimated that they represent approximately 5–10% of benign duodenal tumors. They are variable in size, typically 1–3 cm, with only a few reported cases of lesions larger than 5 cm.
Most patients with Brunner gland hamartomas are asymptomatic or have nonspecific complaints such as nausea, bloating, or vague abdominal pain.
Most reports in the literature describe local surgical resection of Brunner gland hamartoma via duodenotomy. Increasingly, successful endoscopic resection has been reported and is primarily used for
pedunculated Brunner gland hamartomas. The endoscopic approach in selective cases appears to be safe, less invasive, and less costly.
Consistent with the more recent idea that Brunner’s glands influence systemic immunity via the microbiome, patients who had the duodenal bulb removed (where the glands are mostly located) showed greater alterations in immune factors compared to patients having more distal parts of the duodenum removed.
See also
*
Peutz–Jeghers syndrome
*
List of distinct cell types in the adult human body
References
External links
* - "Digestive System: Alimentary Canal: pyloro/duodenal junction, duodenum"
* - "Digestive System: Alimentary Canal: pyloro/duodenal junction"
* - "Digestive System: Alimentary Canal: duodenum, plicae circularis"
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Digestive system