This document provides an overview of the histology of the major salivary glands, including the parotid, submandibular, and sublingual glands. It describes the secretory end pieces composed of serous and mucous cells, as well as the ductal system including intercalated, striated, and excretory ducts. The minor salivary glands are also briefly discussed. The roles of myoepithelial cells and the different cell types involved in saliva production are summarized.

1. Presented by
Dr. Shrikant Sonune
Guided by
Dr Ashok Patil,
Dr Shilpa Kandalgaonkar,
Dr Mayur Choudhari,
Dr Suyog Tupsakhare,
Dr Mahesh Gabhane.

2. Content
 Introduction
 Histology of salivary glands.
 Parotid gland
 Submandibular gland
 Sublingual gland
 Minor salivary gland
 Structure of terminal end pieces
 Ductal system
 Formation of saliva
 Composition of saliva
 Function of saliva.
 Clinical considerations.
 References

4. Histology of major salivary glands
Salivary glands consist of
secretory end pieces that
are composed of
1. Serous cells
2. Mucous cells
3. Mucous end pieces
capped by serous
demilunes

5. Histology of major salivary glands
System of ducts
1. Intercalated, intralobar
2. Striated
3. Excretory– interlobular.
that modify the saliva
produced by the end
pieces and convey it to
the oral cavity.

6.  Contractile
myoepithelial cells are
distributed around the
end pieces & intercalated
ducts.
 The gland is supported
by connective tissue,
which carries the nerve,
vascular & lymphatic
supplies to the
parenchymal component
Histology of major salivary glands

7. Parotid glands
 The spherical secretory
end pieces are all serous
 Pyramidal shaped acinar
cells have a spherical,
basally situated nucleus &
surround a small, central
lumen.
 Fat cell spaces often are
seen in sections of the
parotid gland.

8. Parotid glands
 The intercalated ducts
lined by Cuboidal
epithelial cells & have
Lumina that are larger
than those of acini.
 The striated ducts -
numerous and appear as
singly acidophilic, round
or elongated tubules of
larger diameter than the
end pieces.

9.  The duct consist of simple
columnar epithelium, with
round centrally placed
nuclei.
 The Lumina are large
relative to the overall size
of the ducts.
Parotid glands

10. Submandibular
 Serous end pieces &
mucous tubules capped
with serous demilunes,
thus it is mixed gland.
 Serous cells significantly
outnumber the mucous
cells.
 Pyramidal shaped acinar
cells have a spherical,
basally situated nucleus &
surround a small, central
lumen.

11.  The mucous cells are
filled with pale staining
secretory material &
little cytoplasm is usually
visible.
 Lumina of mucous
tubule are larger than
those of serous end
pieces.
Submandibular

12.  Serous demilune cells are
similar in structure but
discharge their secretions
into small intercellular
canliculi that extend
between the mucous cells to
reach the tubule lumen.
 The intercalated and
striated ducts are less
numerous than those in the
parotid gland, but otherwise
they are structurally similar.
Submandibular

13. Sublingual
 It is also a mixed gland, but
mucous secretory cells
predominate.
 Serous end pieces may be
present, they are rare.
 The intercalated ducts are
short and difficult to
recognize.
 Interlobar ducts are fewer
in number than in the
parotid or submandibular
glands.

14. Minor salivary glands
 Minor salivary glands are found
throughout the oral cavity,
except in the anterior part of the
hard palate & the gingiva.
 These glands consist of
aggregates of secretory end
pieces & ducts, organized into
small lobule like structure
located in the submucosa or
between muscle fibers of the
tongue.
 The minor gland saliva typically
rich in mucins

15. Minor salivary glands
 The ducts draining individual glandular aggregates
usually open directly onto the mucosal surface.
 The secretory end pieces of most minor glands are
mucous or have a small serous component arranged as
occasional demilune.
 In contrast to the usual situation in minor glands, the
lingual serous glands (of vonEbner) in the tongue
below the circumvallate papillae are pure serous glands

16. Minor salivary glands
Functional importance
The minor glands exhibits a continuous slow secretory
activity & thus have important role in protecting and
moistening the oral mucosa, especially at night when
the major salivary glands are mostly inactive.

17. Serous acini
 They are predominant in parotid gland. The acini are
made up of serous cells.
 They have all the features of a cell specialized for the
synthesis, storage, and secretion of protein.
 Serous cells produces proteins & glycoproteins many of
which have well defined enzymatic, antimicrobial,
calcium binding, or other activities.

18. Serous acini
 Serous cells are approximately
pyramidal in shape with broad
base resting on a thin basal
lamina & its narrow apex
bordering on the lumen.
 Nucleus is spherical located in
basal region of cell occasionally
binucleate cells are observed.
 Their nuclei vary in shape and
position, but are more rounded
and situated less basally than in
mucous cells.

19.  Most prominent feature
of the serous cell is the
accumulation of
secretory granules in the
apical cytoplasm.
 In routine histological
preparations, apical
portion of the cell may
appear as an acidophilic
mass.
Serous acini

20.  The basal portion of the
cytoplasm is filled with
rough endoplasmic
reticulum. Specially cells
that produces large
amount of protein for
secretion, the rough
endoplasmic reticulum is
well develop & arranged
in parallel stacks, usually
basal & lateral to
nucleus.
Serous acini

21.  Golgi apparatus is
located apical or lateral
to the nucleus.
 The newly synthesized
secretory proteins within
RER are transported to
the Golgi apparatus via
small vesicles.
Serous acini

22.  Proteins are packed into
vacuoles of different size &
density of these granules are
forming secretory granules &
are called immature granules,
presecretory granules,
condensing vacuoles.
 After that the increase in
density of the secretory
material suggests that it is
being concentrated as it is
being transported & packed
for storage in granules.
Serous acini

23.  After variable period of
storage in cell apex, they
are discharge by
exocytosis at the
secretory surface of the
cell.
Serous acini

24.  Apically, the cytoplasm is
filled by proteinaceous
secretory (zymogen)
granules with high
amylase activity.
Serous acini

25. MUCOUS ACINI
 Mucous acini are made
up mucous cells and are
present in mucous and
mixed salivary glands.
 They produce store, and
secrete proteinaceous
material and smaller
enzymatic component.

26.  Mucous cells typically
have tubular
configuration when cut
in cross section these
tubules appears as round
profile with mucous cell
surrounding a central
lumen of larger size than
that of serous end pieces.
MUCOUS ACINI

27.  In routine histological
preparations the apex of
the cell appears empty
except for thin strands of
cytoplasm compressed
against the base of the
cell.(empty appearance
to the supra-nuclear
cytoplasm.)
MUCOUS ACINI

28.  Most prominent feature of
mucous cells is the
accumulation in the apical
cytoplasm of large
amounts of secretory
product (mucus).
 Droplets are usually larger
than serous granules &
may be irregular or
compressed in shape.
MUCOUS ACINI

29. Secretory product differ
from those of serous cell
in
 They have little or no
enzymatic activity.
 Contains more amount
of carbohydrate.
 They serve mainly for
lubrication & protection
of oral tissue.
MUCOUS ACINI

30.  The nucleus of mucous cell
is oval or flattened in
shape located just above
the basal plasma
membrane
 The rough endoplasmic
reticulum is limited to
narrow band of cytoplasm
along the base & lateral
borders of cell & to an
occasional patch of
cytoplasm, mitochondria,
Golgi apparatus are
dispersed in the same loci.
MUCOUS ACINI

31.  Golgi apparatus plays an
important role in these
cells because of the large
amount of carbohydrates
that it adds to the
secretory products.
MUCOUS ACINI

32.  Mucous cells have large
Golgi complex, located
mainly basal to the mass
of secretory granules.
Small granules form at
the trans face of Golgi
complex, increase in
size, & join the rest of
granules stored in the
apical cytoplasm.
MUCOUS ACINI

33.  Mucous cells are joined
by a verity of
intercellular junctions.
Unlike serous cells,
however mucous cells
lack intercellular
canliculi, except for
those covered by
deminule cells.
MUCOUS ACINI

34. SEROUS DEMILUNE:
 crescents of Giannuzzi ,(crescents of Heidenhain)
 Occasionally and in particular in glands located relatively
close to the oral cavity, serous cells and mucous cells may
form compound or mixed acini.
 The serous cells form in these cases small half-moon or
crescent-shaped structures, which is known as serous
demilune.
 It is attached to mucus producing acini and empties their
secretory product into interstices between the mucus-
producing cells.
 These serous deminule cells are in all respects similar to the
serous end piece cells present in the same gland.
 Their secretions reach the lumen of the end piece through
intercellular canliculi extending between the mucous cells at
the end of tubule.

35. MYOPITHELIAL CELL:
 Myoepithelial cells are
contractile cells associated
with secretory end pieces
and with much of the
ductal system.
 They lie between the basal
lamina and the epithelial
cells proper. They extend
numerous cytoplasmic
processes around serous
acini and are often termed
basket cells.

36. MYOPITHELIAL CELL:
 Myoepithelial cells
associated with ducts are
more fusiform in shape,
and are aligned along the
length of the duct.
 Their cytoplasm contains
abundant actin
microfilaments which
mediate contraction under
the control of both
sympathetic and
parasympathetic
stimulation.

37. MYOPITHELIAL CELL:
 The outflow of saliva is
thus accelerated through
reduction in the luminal
volume of secretory end
pieces and ducts,
contributing to the
secretory pressure.
 Contraction of the
myoepithelial cells thought
to provide support for the
end pieces during active
secretion of saliva.

38. MYOPITHELIAL CELL:
 They provide signals to the acinar secretory cells that
are necessary for maintaining cell polarity & the
structural organization of secretory end piece.
 Myoepithelial cells produces a number of proteins that
have tumour suppressor activity such as proteinases
inhibitors (tissue inhibitor of metalloproteinase) &
anti angiogenesis factors & these cells may provide a
barrier against invasive epithelial neoplasms.

39. Ductal System
 A salivary gland consists of a series of branched
ducts, terminating in spherical or tubular secretory
end pieces or acini.
 The main excretory duct, which empties into oral
cavity, divides into progressively smaller interlobar
and intralobular excretory ducts that enter lobes and
lobules of the gland.

40. Ductal system
 The three classes of
ducts are intercalated,
striated & excretory each
with differing structure
& function.
 Ductal system actively
participates in the
production &
modification of saliva.

41. Intercalated Ducts
 The first cells of the intercalated duct are directly
adjacent to the secretory cells of the end pieces, and
the lumen of the end pieces is continuous with the
lumen of the intercalated duct.
 The intercalated ducts are lined by a simple Cuboidal
cells, & myoepithelial cell bodies & their process
typically are located along the basal surface of the
duct.
 The overall diameter of the intercalated ducts is
smaller than that of the end pieces, & their Lumina are
larger than those of the end pieces.

42. Intercalated Ducts
 Several ducts draining individual end pieces join to
form larger intercalated ducts before empting into the
striated ducts.
 The intercalated ducts cells have centrally placed
nuclei & a small amount of cytoplasm containing some
rough endoplasmic reticulum & small Golgi complex.
 Intercalated ducts often are difficult to identify in
routine histologic sections.

43. Intercalated Ducts
 The intercalated ducts contribute macromolecules which
are stored in their secretory granules to the saliva. These
components involve lysozyme and lactoferrin, along with
the other unknown component.
 A portion of the fluid component of the primary saliva
likely is added in the intercalated duct region.
 Undifferentiated cells, thought to represent salivary stem
cells, are believed to present in the intercalated ducts.
These cells may proliferate & undergo differentiation to
replace damage or drying cells in the end pieces & striated
ducts.

44. Striated Ducts
 The striated duct, constitute the largest portion of
ducts are the main Ductal component located within
the lobules of the gland, that is intralobular.
 The overall diameter of the ducts is greater than that
of the secretory end pieces & lumen is larger than
those of the secretory end pieces & intercalated ducts.
 The basal lamina encloses the striated duct, & a
capillary plexus is present in the surrounding
connective tissue.
 Striated duct cells are columnar with centrally placed
nucleus & pale, acidophilic cytoplasm.

45. Striated Ducts
 The apical cytoplasm may contain small secretory granules
& electron lucent vesicles.
 The presence of vesicles suggests that the cells may
participate in endocytosis of substances from the lumen.
 Numerous lysosomes and peroxisomes and deposits of
glycogen frequently are present in perinuclear cytoplasm.
 Adjacent cells are joined by well developed tight junctions
& junctional complexes but lack gap junctions.
 An important function of striated duct cell is modification
of the primary saliva by reabsorption and secretion of
electrolytes.

46. Excretory ducts
 The excretory ducts are located in the connective
tissue septa between the lobules of the gland, thus it is
having extra lobular & inter lobular locations.
 These ducts are larger in diameter & than striated
ducts and typically have Pseudostratified epithelium
with columnar cells extending from the basal lamina
to the Ductal lumen
 Small basal cells that sit on the basal lamina but do not
reach the lumen.

47. Excretory ducts
 The epithelium of main excretory duct may become
stratified near the oral opening.
 In the smaller excretory ducts the structure of the
columnar cells is similar to that of the striated duct
cells.
 The basal cells have a high rate of proliferation.

48. Other type of cell include
1. Tuft (caveolated or brush) cells, with long stiff microvilli &
apical vesicles, are thought to be receptor cells of some
type. Nerve endings occasionally are found adjacent to the
basal portion of these cells.
2. Lymphocytes & macrophages- cells with pale cytoplasm an
dense nuclear chromatin may be found toward the base of
the duct epithelium.
3. Dendritic cells – the cells have long branching processes
that extend between the epithelial cells. These are antigen
presenting cells, that are involved in immune surveillance
& the processing & presentation of foreign antigens to T
lymphocytes.

49. Connective tissue
 The connective tissue of salivary glands includes a
surrounding capsule, variably developed, that
demarcates the gland from adjacent structure.
 Septa that extends inward from the capsule divide the
gland into lobes and lobules and carry blood vessels
and nerves that supply the parenchymal components
and the excretory ducts that convey saliva to the oral
cavity
 The cells of connective tissue include fibroblasts,
macrophages,mast cells, plasma cells, adipose cells and
occasionally granulocytes and lymphocytes.

50. Connective tissue
 Collagen and elastic fibers along with the
glycoproteins and proteoglycans of the ground
substance constitute the extracellular matrix of the
connective tissue.
 Within the lobules of the gland, finer partitions of
connective tissue extend between adjacent secretory
end pieces and ducts.
 These partitions carry the arterioles, capillaries and
venules of the microcirculation & the finer branches of
the autonomic nerves that innervate the secretory &
Ductal cells.

51. Nerve supply
 Within the gland lobule, branches of the nerves follow
the blood vessels, eventually forming a plexus of
unmyelinated fibers adjacent to arterioles, ducts and
secretory end pieces.

52. Blood supply
 Salivary glands necessities an extensive blood supply.
 One or more arteries enter the gland & give rise to smaller
arteries & arterioles, exist around the excretory ducts.
 The arterioles break up into capillaries that are distributed
around the secretory end pieces & striated ducts.
 An extensive capillary plexus also arising from separate
arterioles exist around the excretory ducts.
 The endothelium of the capillaries & post capillary venules
is fenestrated.
 The venous return generally follows arterial supply.

53. Formation of saliva.
 The formation of saliva occurs in two stages
 In 1ststage cells of secretory end pieces & intercalated
ducts produce primary saliva.
 In the second stage the primary saliva is modified as it
passes through the striated and excretory ducts,
mainly by reabsorption & secretion of electrolytes.
 The final saliva that reaches the oral cavity is
hypotonic.

54. MACROMOLECULAR
COMPONENTS
 The cells of the secretory end pieces, Secretory
proteins are synthesized by ribosome attached to the
Cisternae of the endoplasmic reticulum and
translocated to the lumen of the endoplasmic
reticulum.
 The proteins are transferred by small vesicles to the
Golgi complex, where they undergo further
modification, followed by condensation as packaging
into secretory granules.

55. MACROMOLECULAR
COMPONENTS
 The secretory granules are stored in the apical
cytoplasm until the cell receives an appropriate
secretory stimulus. The contents are released into
lumen by process of exocytosis.
 The effective stimulus for exocytosis is nor epinephrine
(sympathetic neurotransmitter).

56. Fluid & electrolytes
 Secretion of water by the cells of the secretory end
pieces is regulated by the parasympathetic
innervations.
 Hypertonic secretion draws ions in to the luminal
spaces. That draws the water from the cells to luminal
spaces by active mechanism.

57. Composition of saliva
Parameter Characteristics
Volume 600-1000 ml/day
Electrolytes Na+ ,K+ ,Cl- , HCO3- ,Mg++
HPO4-- ,SCN- , F-
Secretory proteins Amylase, proline rich
proteins,mucins,histatins,
cystatins,peroxidase,
lysozyme, lactoferrin
Immunoglobulins IgA, IgG, IgM
Small organic molecules Glucose, amino acids, urea,
uric acid and lipids
Other components Insulin, serum albumin

58. Function of saliva
 Protection-Clearance, lubrication, thermal & chemical
insulation, pellicle formation, tannin binding.
 Buffering – ph maintenance, neutralization of acids.
 Tooth integrity- enamel maturation & repair.
 Antimicrobial activity- physical barrier, immune defense,
non immune defense.
 Tissue repair -wound healing, epithelial regeneration.
 Digestion -bolus formation, amylase, lipase
 Taste-solution of molecules, maintenance of taste buds

59. Clinical consideration
 Age changes
 Disease
 Structural (histogenesis of various diseases).
 Functional condition

60. Age changes
 Generalized loss of parenchymal tissue.
 Lost salivary cells often replaced by adipose cells.
 Increase in fibrous connective tissue.
 Decrease in production of saliva.

61. Diseases
 Affected by local, systemic disease
 Endocrine, autoimmune, infectious disease.

62. Developmental malformation
 Aplasia.
 Atresia.
 Stafnnes cyst.
 Fordyce's granules.

63. Functional condition
 Xerostomia
 Ptylism

64. References
 Ten Cate’s Oral histology Development, Structure and
Function Sixth Edition
 General Anatomy 3rd vol. by B. D. Chaurasia
 Textbook of Human Histology Inderbir Singh
 Textbook of Oral and maxillofacial Surgery by Neelima
Malik

65. Thank you