Chapter 14
Accessory Glands of the Gastrointestinal Tract
215
Basic Structure of Salivary Glands
Stroma
Parenchyma
(Fig. 14.1)
Duct system
(Fig. 14.1)
●●
Connective
tissue
capsule and
its septa
●●
Serous acini
: Cells are triangular in shape with
round nuclei at their bases; apical cytoplasm
is eosinophilic and basal cytoplasm is
basophilic
●●
Mucous acini
: Cells are tall with flat nuclei at
their bases, empty-looking cells due to pale
cytoplasm
●●
Serous demilunes
: Serous cells arranged as a
‘half moon’ at one end of a mucous acinus
●●
Intercalated
: Simple cuboidal epithelium
●●
Striated
: Simple cuboidal epithelium; cells
have basal striations
●●
Interlobular
: Simple columnar epithelium
in small ducts and stratified columnar
epithelium in large ducts
●●
Terminal part
: Stratified squamous
non-keratinised epithelium
Different Types of Salivary Glands
Gland
Secretory acini
Differentiating features
Parotid
(Fig. 14.2; PMG 14.1)
Serous
Darkly stained serous acini (note that
pancreas also has similar appearance,
but it has islets of Langerhans)
●●
Contraction of these muscles (when stimulated by cholecystokinin) causes expulsion of contents of
the gallbladder into the cystic duct.
Adventitia and Serosa
●●
The part of the gallbladder covered with peritoneum has serosa and the part not covered with perito-
neum has adventitia (like other retroperitoneal organs).
●●
On microscopic examination, mucosal folds of the gallbladder appear like the villi of small intestine.
One of the important differentiating features is the presence of goblet cells in the mucosa of small
intestine, which are absent in the gallbladder. Another differentiating feature is that in a particular
region of small intestine, the size and shape of the villi are same, whereas in the gallbladder, the size
and shape of the mucosal folds vary.
Salivary Glands
●●
Benign tumours arising from the cells of ducts or myoepithelial cells are called pleomorphic adenoma.
Warthin tumour is a benign tumour of parotid glands.
Liver
●●
Cirrhosis refers to irreversible chronic injury of the liver parenchyma, which results in disruption of the
normal architecture of the entire liver. It is characterised by death of hepatocytes and scarring. Attempted
regeneration of remaining hepatocytes results in irregular nodules, distortion of vascular architecture.
Most common cause of cirrhosis of
liver is alcoholic liver disease.
Pancreas
●●
Pancreatitis is the inflammation of the pancreas. In acute pancreatitis there is collection of inflammatory
infiltrate in the stroma. Release of pancreatic enzymes can cause proteolytic digestion, haemorrhage and
necrosis. It can become life-threatening. Common causes are alcoholism, gallstones, trauma, etc. Chronic
pancreatitis can lead to fibrosis of the parenchyma.
CLINICAL CORRELATES
KEY POINTS
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continued
)
