new salivary histo......................

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1. SALIVARY GLANDS
DR. NIDA JAWED

2. Introduction
•Saliva is produced by three pairs of major salivary glands, the
parotid, submandibular and sublingual glands, and
numerous minor accessory glands scattered throughout the
oral mucosa.
•The minor salivary glands secrete continuously and are in
general under local control, whereas the major glands
mainly secrete in response to parasympathetic activity which
is induced by physical, chemical and psychological stimuli.
•Daily saliva production in humans is 600 to 1500 mL.

4. •Acini and their duct
system resemble grapes
attached to a stem that’s
why these glands are
included in the
tubuloacinar variety of
glands.

5. Secretions
a)Serous: produces a watery secretion,
usually glycoproteins that are enzymes.
b)Mucous: produces secretion that is high in
carbohydrates (about 50% protein, 50%
carbohydrates).
c)Mixed: acinus is composed of both serous
and mucous cells, or there is a mucous acinus
with aserous demilune.

6. Difference between Serous & Mucous
Acini
Serous
•Thin, watery
•Proteinaceoussecretion
•Zymogengranules in cyto
•Central rounded Nucleus
•Small Lumen
•Indistinct cell bondaries
•Darkly stained
•Enzymatic action
•Parotid Gland
Mucous
•Thick, viscous
•Mucopolysaccharides
•Mucigendroplets
•Nucleus-flat & peripheral
•Large Lumen
•Distinct cell boundaries
•Lighlystained
•Protection & lubrication
•Sublingual gland

7. Salivary glands

8. Salivary Glands
Major Salivary Glands
Minor Salivary Glandslingual,
labial, buccal, molar, and palatine glands.
Parotid Gland
Submandibular Gland
Sublingual Gland:
Von Ebner`s glands

9. •Minor Salivary Glands:
These are small
compound glands located
throughout the oral
cavity beneath the
epithelium.
•These can be mucous,
serous or mixed, and
depending on the size
may show intercalated
and striated ducts, as well
asshort collecting ducts
that empty into the
mouth.
•e.g.Von Ebner`s glands
under the circumvallate
papillae in the tongue are
minor salivary glands

10. Parotid Gland: The
largest salivary
gland. A well
encapsulated gland
located in the side of
the face.
It is apure serous
gland
The compound duct
system shows
intercalated, striated
and collecting ducts.
The main duct opens
on the inside of the
cheek, just opposite
to the upper
2ndmolar tooth. The
duct is called
Stenson's duct.

11. Parotid gland compound tubuloalveolar
glands (serous type)
The parotid glands are the largest salivary glands located in each
cheek near the ear, it is a branched tubuloacinar gland with
secretory portions composed exclusively of serous cells surrounding
very small lumens.
Numerous septa having arterioles, venules, interlobular ducts &
adipose cells.
Only Serous acini having pyramidal cells.
Myoepithelial cells between basement membrane and serous cells.
Intercalated ducts, striated ducts, interlobular excretory ducts, lobar
ducts.
Serous cells contain secretory granules with abundant -amylase
and proline-rich proteins. Amylase activity is responsible for most
of the hydrolysis of ingested carbohydrates which begins in the
mouth. Proline-rich proteins, the most abundant factors in parotid
saliva, have antimicrobial properties and Ca2+ binding properties
that may help maintain the surface of enamel.

12. •Submandibular Gland: Also well encapsulated. This gland consists
of90% serousaciniand10% mucousacini so it is a mix variety of
gland.
•The mucous acini occur in small patches distributed throughout the
gland.
•Some mucous acini may be mixed, or show serous demilunes.
•The duct opens under the tongue and is called Wharton's duct.

13. Submandibular gland
•is a branched tubuloacinar gland , with secretory
portions containing both mucous and serous cells.
•The serous cells are the main component of this
gland and are easily distinguished from mucous cells
by their rounded nuclei and basophilic cytoplasm.
•Most of the secretory units in this gland are serous
acinar, with about 10% consisting of mucous tubules
capped with serous cells. Such caps are called serous
demilunes.

14. Submandibular gland
•is a branched tubuloacinar gland , with secretory
portions containing both mucous and serous cells.
•The serous cells are the main component of this
gland and are easily distinguished from mucous cells
by their rounded nuclei and basophilic cytoplasm.
•Most of the secretory units in this gland are serous
acinar, with about 10% consisting of mucous tubules
capped with serous cells. Such caps are called serous
demilunes.

15. Sublingual Gland
(dashed circle):A small
gland on either side of
the midline of the tongue
in the floor of the mouth.
It is poorly encapsulated
and has mixed acini,
mainlymucous with
serous aciniand
demilunes.
The duct is called
Rivinus' ducts that open
at numerous sites along
the connection of the
tongue to the floor of the
mouth.

17. Sublingual gland
Like the submandibulargland, is a branched
tubuloacinargland formed of serous and
mucous cells.
Major salivary product is mucus, but cells of the
serous demilunesin this gland secrete amylase
and lysozyme.

18. PARENCHYMA
The parenchyma of
each salivary gland are
made up of secretory
end pieces acini(acini -
means a rounded
secretory unit) and a
branching duct system
arranged in lobules,
separated by
connective tissue septa
originating from the
capsule.

20. Acinus The acinus is a blind sac composed of secretory cells. The
term acinus [L., berry or grape] refers to the secretory unit of the
salivary glands.
The acini of salivary glands contain either serous cells (protein
secreting), mucous cells (mucin secreting), or both.

21. •Acinar cellsare usually pyramidal in shape, with a broad base
resting on the basal lamina and a narrow apical surface facing the
lumen

22. Adjacent cells are joined together by junctional complexes and
usually form a spherical mass of cells called an acinus,with a very
small lumen in the center.

23. serousmucous
secretory glands
Two major kinds of secretory cells occur, arranged in separate units
that is Serous cells and mucus cells making Serous and mucus
glands.

24. Serous Glands
Serous secretions have a low
viscosity, i.e. they are rather
"watery".
•The terminal portion of a serous
gland duct has the form of an
acinus.
•The apical cytoplasm of the cells
formingserous aciniis usually
well-stained.
•The acinar lumina are narrow.
•They display round nuclei and
an elaborate ergastoplasma
(network of cytoplasmic
structures that show basophilic
staining properties; granular
endoplasmic reticulum).
•Staining clearly reveals secretory
granules in the supranuclear cell
space. The cytoplasm is therefore
granulated.
•Between glandular cells are
intercellular secretory canaliculi.
•E.g. Human parotid gland

26. •Mucous Glands
•Mucous secretions have a high viscosity, i.e.
they are rather "slimy".
•Most terminal portions of mucous glands are
tubular (glands with tubular terminal
portions).
•The contents of the secretory vesicles in the
apical cytoplasm of cells formingmucous
aciniare only weakly stained.
•The total lumen is larger than that in serous
gland acini.
•The lumina are relatively wide.
•the nuclei are flattened and distorted and
look like sickles or spindles. Nuclei are
always located in the basal cell region.
•Basal basophilia does not exist, or is barely
detectable after staining. The cell bodies of
mucous gland cells display large, only
lightly stained secretory granules, which
occupy most of the cellular space. These
stacked granules cause the cytoplasmic
honeycomb structure
•The cell borders are clearly visible. In the
apical regions are terminal bars .
•There are no intercellular secretory
canaliculi.
•E.g. Human sublingual & submandibular
gland.

30. Serous Cells
Usually arranged as acinar
secretory units.
The cells are pyramidal shaped
with a broad base resting on
the basal lamina and a narrow
apical surface facing the
lumen, Adjacent cells are
joined together by junctional
complexes and usually form a
spherical mass of cells called
an acinus (a spherical unit
with the apices of the cells
meeting to form a small lumen)

31. •The cells secrete glycoproteins, mostly enzymes that are contained in
the secretory granules as an inactive enzyme, or zymogen, hence the
name of the granules. These acini are usually drained by a small duct
called anintercalated duct.

33. Mucous Cells (mucus)
•Mucous cellsare somewhat more cuboidal or columnar in
shape.

34. Apical region of each mucus cell is
occupied by numerous mucinogen
granules whose proteins have a high
sugar content. The secretory product of
these granules is calledmucin or mucus.

36. Myoepithelial cells (sometimes referred to as
Myoepithelium) are cells usually found in glandular
epithelium and (to a lesser extent) the initial part of the
duct system as a thin layer above the basement membrane
but generally beneath the luminal cells.
Myoepithelial cells

37. •It has body and
many long
processes
which contain
actin &
myosin.

38. Serousdemilunes
•In mixed acini where
mucous cells
predominent,serous cells
form crescent or moon
shaped cap over the
mucous cells called serous
demilunes.

41. Organization of Glands and Ducts
•Thecapsulea layer of dense connective tissue rich in collagen fibers covering the
outer aspect of the gland. The capsular connective tissue continues into the gland
and subdivides it into lobes and lobules
•The connective tissue carries the blood supply to the glandular units, but it also
carries the duct system, thus, ducts can be named by their location as well as by their
structure.

42. Mucus tubule

43. Ducts
•All of the larger glands are compound glands with an
extensive duct system. Duct systems share common
features, and three divisions are recognized:
1)Intercalated; 2)Striated; and 3)Collectingducts.
•Intercalated Ducts: Leading from their secretory
units are intercalated ducts.These are the smallest
ducts, being much smaller than the diameter of the
acini. They are lined by simple squamous epithelium
or simple low cuboidal epithelium that is partly
invested by myoepithelial cells and have a very small
lumen.

45. Striated Ducts
•These striations correspond to basal infoldings and interdigitations of
the cell membrane with numerous more or less parallel associated
mitochondria.
•The nuclei of cells are round and near the base. The cytoplasm is
deeply eosinophilic and striated due to extensive basal membrane
infolding and elongated mitochondria.

46. •Collecting Ducts:
•The striated ductsof each lobule converge and drain
into ducts located in the connective tissue septa
separating lobules, where they become interlobular,
or excretory ducts they are lined by simple
epithelium, either cuboidalin small ducts or
columnar in larger ducts
•The interlobular ductsjoin to form the interlobar
ductswhich is lined by pseudostratified columnar
epithelium.
•The interlobular ductsultimately drains into main
ductof gland which is lined with stratified columnar.
•The main ductof each large salivary gland ultimately
empties into the oral cavity and is lined with
nonkeratinized-stratified squamous epithelium near
its opening into oral cavity.

51. •PAROTID GLAND
•(a) Densely packed serous acini only.
•(b) Intercalated ducts are large, striated ducts, Interlobular,
or excretory ducts, Interlobar ducts
•SUBMANDIBULAR GLAND
•(a) Secretory portions containing both mucous and serous
cells. The serous cells predominate from mucous cells.
•(b) Intercalated ducts, large striated ducts, Interlobular,
Interlobar ducts
•SUBLINGUAL GLAND
•(a) Secretory portions containing both serous and mucous
cells. Here mucous cells predominate, with serous cells
only present in demilunes on mucous tubules.
•(b) Intercalated ducts, small striated ducts, Interlobular,
Interlobar ducts