Salivary glands

Topic Completed: 1 September 2015

Minor changes: 12 March 2020

Copyright: 2002-2020,, Inc.

PubMed Search: Salivary glands[TI] histology[TIAB]

Sally Tanakchi, M.D.
F. Zahra Aly, M.D., Ph.D.
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Cite this page: Tanakchi S, Aly FZ. Histology. website. Accessed September 26th, 2020.
Definition / general
  • Exocrine glands with ductal and acinar portions
  • Acinar portion is serous, mucinous or mixed
  • Acini are lined by luminal cells, which are enclosed by myoepithelial cells

  • Serous acini:
    • Dense, basophilic, PAS+ intracytoplasmic secretory granules containing amylase
    • Have central lumen that is rarely visible by H&E
  • Mucinous / mucous acini:
    • Larger than serous acini
    • Irregular pattern
    • Cells have abundant cytoplasm with clear mucin, well rounded basal nuclei and are arranged around empty lumina
    • Produce acid (positive for Alcian blue and mucicarmine) and neutral (PAS+) sialomucins
  • Myoepithelia cells:
    • Surround acini and intercalated ducts and mediate contraction
    • Have both epithelial and mesenchymal structures and functions and are important in the morphology of most salivary gland tumors
    • Myoepithelial cells surrounding intercalated ducts are more spindled and have fewer processes than those surrounding acini
  • Ducts:
    • Either intercalated, striated or interlobular, all with outer basal cells and inner luminal cells
    • Intercalated ducts have reserve cells that regenerate acinar tissue and terminal duct system
    • All epithelium is PAS+ (Pathol Int 1999;49:500)
    • Sebaceous glands are attached to parotid and submandibular ducts and are considered part of normal holocrine differentiation (holocrine secretions are produced within the cell, then are released into the lumen after rupture of the plasma membrane), based on the occurrence of salivary tumors with sebaceous differentiation (Am J Surg Pathol 1989;13:879)
    • Sebaceous type glands are mixed with salivary gland acini in 10 - 40% of normal parotid glands, often in periductal locations in interlobular ducts; either single, isolated sebaceous type cells within serous or mucinous salivary acini or as fully developed sebaceous glands (Arch Pathol Lab Med 2004;128:245)
  • Parotid gland:
    • Serous acini only; contain numerous basophilic zymogen granules; nuclei are uniform, round and in the basal half of the cell
    • Intercalated ducts are long in comparison to striated ducts
    • Striated ducts are larger than intercalated ducts, 3 - 6x size of acinus; striations are due to folds in basal plasma membranes
    • Contains small lymph nodes near or within the gland, which arise from interstitial lymphocytes
    • Resembles pancreatic tissue but parotid gland had adipocytes and pancreatic tissue has islets and centroacinar cells
  • Submandibular gland:
    • Predominantly serous but also mucinous acini
    • Mucous cells are the most active and therefore the major product of the submandibular gland is saliva which is mucoid in nature
  • Sublingual gland:
    • Predominantly mucinous but also serous acini
  • Basement membrane protein perlecan / HSPG2 (heparan sulfate proteoglycan 2) triggers differentiation of salivary gland cells into self assembling acini-like structures that express essential biomarkers and secrete alpha amylase (Tissue Eng Part A 2009;15:3309)
  • Serous glands produce thin watery fluid containing alpha amylase, which digests starches
  • Mucinous glands produce viscous mucinous fluid higher in glycoproteins, which provides a lubricating film on oral mucosa
Diagrams / tables

AFIP images
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Cytomorphologic features of various portions of the
salivary system from the secretory end piece to the
oral cavity; from left to right: the acinus, intercalated
duct, striated duct, excretory duct, oral cavity

Microscopic (histologic) images

AFIP images

Parotid gland
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Clusters of large, pale staining mucous cells (arrows) occasionally
are present in the parotid gland but the acini are overwhelmingly of
serous type; each serous acinus is composed of several pyramidal
shaped cells with basal nuclei and basophilic cytoplasmic granules

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Serous cell granules
are PAS+ and resistant
to diastase digestion
(PAS stain)

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Cells of the intercalated duct (arrow) are
small in comparison to the acinar cells and
are cuboidal with pale stained cytoplasm
and central nuclei; small lumen is evident

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This small, interlobular excretory
duct is lined by pseudostratified
columnar epithelium and embedded
in dense fibrous connective tissue

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Striated duct is larger than an acinus and much larger
than the intercalated duct; ductal cells are eosinophilic
columnar cells with central nuclei and vertical cytoplasmic
striations due to folds in the basal plasma membranes

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Facial nerve branches in parotid gland: relatively large
nerve lies adjacent to a lobule of parotid glandular
tissue (left) while a smaller nerve branch is within
a lobule and in contact with serous acini (right)

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Intraglandular adipose tissue in parotid gland: parotid gland from
neonate contains no discernible adipose tissue; moderate amount of
intralobular adipose tissue in parotid tissue from middle aged adult;
intraparotid adipose tissue is quite prominent in gland from elderly person

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Sebaceous cells in parotid gland: cells in 2 foci of sebaceous differentiation
(arrows) are large with central nuclei and clear reticulated cytoplasm
that is unreactive with mucicarmine stain; small foci of sebaceous cells
occur frequently in the parotid gland (mucicarmine stain)

Submandibular gland
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In submandibular gland, mucous acini comprise about 10% of acinar tissue;
serous cells are frequently located at the periphery of mucous acini as
crescent shaped cells (arrow); striated ducts (arrowheads) are more prominent
and the intercalated ducts are shorter than those in the parotid gland

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Mucous cells are
highlighted among the
serous acini as rose pink
cells (mucicarmine stain)

Sublingual gland
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Sublingual gland acini are typically
elongated tubules of mucous cells
with serous cell demilunes (a demilune
is a cap in the shape of a half moon)

Minor salivary glands of palate
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Palate contains the largest foci
of intraoral salivary gland tissue,
which is composed of mucous
acini but no striated ducts

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At high magnification, the mucous acini are round
with central lumens; mucous cells are pyramidal
with very pale granular cytoplasm and nuclei
located next to the basal plasma membranes

Minor salivary glands of tongue
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Minor salivary glands are small aggregates
of unencapsulated mucous or serous
glands; in the tongue they are in intimate
contact with the striated muscle tissue

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Keratin cocktail stains intercalated,
striated and interlobular ducts but
acinar and myoepithelial cells are
mostly negative

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Normal parotid tissue is S100 negative

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In this parotid tissue adjacent
to a mixed tumor, some of the
myoepithelial and intercalated
duct cells are S100+

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Normally indistinct, elongated and flattened myoepithelial
cells at the periphery of the acini, intercalated ducts and
striated ducts are conspicuous due to their
immunostaining for alpha smooth muscle actin

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Serous acinar cells immunostain for alpha amylase

Images hosted on other servers:

Parotid gland:
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Replacement of serous glands by sebaceous glands

Positive stains
Electron microscopy description
  • Acinar cells:
    • Numerous cytoplasmic secretory (zymogen) granules in apical portion of cell
    • Extensive rough ER and golgi
    • Numerous mitochondria
    • Numerous folds are present in basal lamina of acinar cells that are not distended with secretory product
    • Mucous acinar cells have larger, more irregular secretory droplets that are more electron lucent than in serous acinar cells
  • Intercalated duct cells:
    • Few special ultrastructural features
    • May have some secretory granules
    • Scant cytoplasm has basal rough ER, apical Golgi and mitochondria
    • Lateral membranes interdigitate with neighboring cells
  • Myoepithelial cells:
    • Between basal plasma membrane of acinar and intercalated duct cells and basal lamina
    • Flattened and elongated with cytoplasmic processes extending around acinar and intercalated duct cells
    • Long / irregular nuclei
    • Desmosomes attach the myoepithelial cells to acinar and ductal cells
  • Striated duct cells:
    • Striations are due to basal vertical folds
    • Numerous mitochondria present
Electron microscopy images

AFIP images
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Variable sized secretory granules occupy most of the apical portion of the cytoplasmic compartment;
parallel arrays of rough endoplasmic reticula lie adjacent to the basally located, round nucleus;
intercellular space contains interdigitations of adjacent cells and represents a canaliculus that is
connected to the acinar lumen and is actually the beginning of the duct system (x11,300)

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Myoepithelial cell lies between the basal lamina and the basal
plasma membranes of the acinar cells; cell body is flattened
and the nucleus is elongated; in the cytoplasm are numerous
microfilaments with focal dense bodies (arrow) (x13,300)

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Basal plasma membranes have prominent vertical folds
and there are numerous mitochondria; lateral surfaces have
processes that interdigitate with adjacent cells; apical junctional
complexes and desmosomes connect adjoining cells (x6,000)

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Relatively small cytoplasmic compartment contains a round nucleus,
mitochondria, lipid vacuoles and an endoplasmic reticulum; there are a
few short microvilli on the luminal surface and intercellular connections
are apical junctional complexes with several desmosomes (x6,000)


Shotgun histology parotid gland

Shotgun histology submandibular gland

Shotgun histology sublingual gland

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