Salivary glands dina+sahar audio 2

Salivary Glands
Oral cavity
proper
Oral
vestibule
Salivary glands are merocrine exocrine glands that
produce and secrete saliva in the oral cavity.

•Classifications
•Of Salivary Glands

1- Labial Gs.
2- Buccal Gs.
3- Parotid Gs.
1- Palatine Gs.
Hard palate
Soft palate
Uvula
2- Mouth floor
Gs.
Sublingual G.
Submandibular G.
Glossopalatine G.
3- Gs. of
tongue
Blandin-Nuhn G.
von Ebner G.
Weber G.
I- According to location
A- Glands of oral
vestibule
B- Glands of oral cavity
proper

II- According To Size
A- Major S G B- Minor S G
1- Parotid ☻Labial & buccal Gs.
2- Submandibular ☻Palatine Gs.
3- Major sublingual ☻Minor sublingual.
☻Lingual Gs.
☻Glossopalatine G.

III- According To The Nature Of
Secretion
A- Pure serous B- Pure mucous C- Mixed
Parotid G. (adult) Palatine Gs Labial and buccal Gs
von Ebner Gs Glossopalatine Gs Submandibular Gs
Weber Gs Major sublingual
Minor sublingual Blandin-Nuhn Gs
Parotid ( Infant and old age)
Mucous Ring

Mucous ring is the minor
pure mucous glands that
are all localized forming a
ring in the posterior
portion of the oral cavity to
facilitate the process of
food swallowing after its
mastication.

mucous
mixed
CT stroma
capsulesepta
lobe
lobule
Parenchymal element
CT. element
Structure of Salivary Gland

Secretory end pieceIntercalated duct
Striated duct
Excretory duct
Parenchymal element
Myoepithelial cell
septa

Structure of Salivary Gland
I- Parenchymal Tissue II- Connective Tissue
(Epithelial part)
1- Secretory terminal portions 1- Capsule
Acini ( Serous, mucous or mixed) 2- C.T. septa
3- Stroma
2- Duct system
☻Intercalated (neck) duct
☻Striated (secretory) duct
☻Excretory duct
☻Main duct
3-Non-secretory cells
A- Myoepithelial cells
B-Oncocytes

Epithelial Structures Of Salivary Gland

•1- Secretory Terminal
Portion

Serous aciniA-
*Spherical or rounded
small acini
*Narrow lumen
*cells are pyramidal
The cytoplasm is basophilic
due to its high content of
RNA. The apical
cytoplasm is filled with
eosinophilic secretory
zymogen granules
*Spherical nucleus in
Basal 1/3
1-Secretory terminal portions

•At the apical ends of the adjoining cells, the
lumen is sealed off by junctional complex,
•The function of junctional complex:
•1-Holds the cells together.
•2-Prevents leakage of the luminal content
into the intercellular spaces.
•-
•Intercellular canaliculi (fingerlike branches of the
lumen) extend between adjacent cells .They
increase the area of the secretory surface..

Ultra structure of serous cells:
1-Large open-face nucleus basally
2-Apical cytoplasm contains
zymogen secretory granules
3-basal cytoplasm full of
organelles.
4-Cytoplasmic organelles:
a-Mitochondria, b-Golgi saccules
c-Lysosomes, d- free ribosomes, e-RER
5-Intercellular canaliculi sealed by junctional
complexes
1
a
b
2
e
5

•The serous secretion has a high percentage of water and proteins and
a low amount of carbohydrates.
•The basal cytoplasm contains abundant rough endoplasmic reticulum
(RER) packed basally and laterally to the nucleus.
•♦ The Golgi apparatus consists of several stacks of 4 to 6 in number.
•♦ The mitochondria contains the enzymes of citric acid cycle, (power
house).
•♦ Free ribosomes (concerned with synthesis of non-secretory cellular
protein).
•♦ Lysosomes (contain hydrolytic enzymes).
•To destroy foreign materials taken by the cells or portions of the cell as
degenerated organelles.
•♦Few peroxisomes. They participate in the lipid metabolism.
•♦ Bundles of tonofilaments

Mitochondria RER
Free ribosomes Golgi apparatus
Ultra structure:

B- Mucous acini
*Tubular long acini
*Larger lumen
*Low pyramidal or
flattened cell
The cytoplasm is small and
acidophilic with
less amount of RNA. The apical
cytoplasm is filled with mucous
secretory mucigen granules.
(With H&E the apical part of the cell
appears empty because these
granules are dissolved.
*Flattened or angular
nucleus present basally

Ultra structure:
1- Nucleus basally compressed
2- Cytoplasm:
A-Vaculated lightly stained
B- the cells appear empty Except:
A thin rim of cytoplasm forming
network
3- Cytoplasmic organelles:
a-mitochondria,
b-Prominent Golgi saccules
C- few RER,
d- few microvilli
4- Very few intercellular
canaliculi
1
Aa
b
RER
Vaculated cytoplasm

•The mucous secretion has a less percentage of
water and proteins and a larger amounts of
carbohydrates.
•The organelles are mainly limited to a thin band of
cytoplasm at the basal and lateral regions of the cell.
•♦ The Golgi apparatus is extensive, consisting of
10 to 12 flattened saccules.
•The large size of the Golgi apparatus reflects its role in
addition of the large amount of carbohydrate to the
mucous secretory products.
•♦The secretory granules are larger and more irregular
in shape than the serous cells.
•The mucous droplets are electron lucent.

Serous Acinus Mucous Acinus
- The serous cell is pyramidal in
shape having a broad base resting on
a basement membrane and a narrow
apex bordering a narrow lumen.
- The mucous cell is low
pyramidal in shape and larger than the
serous cell. It has a broader apex
bordering a wide lumen.
L
L
Small rounded acini, narrow lumen Larger oval acini, wide lumen
•The cytoplasm is strongly basophilic
due to its high content of RNA. The
apical cytoplasm is filled with
eosinophilic secretory granules
known as zymogen granules.
- The nucleus is spherical in shape
and located in the basal portion of
the cell.
- The cytoplasm is acidophilic with
less amount of RNA. The apical cytoplasm is
filled with mucous secretory droplets of high
carbohydrate content (mucigen granules).
With H&E the apical part of the cell appears
empty because these granules are dissolved.
- The nucleus is oval or flattened and
located toward its base surrounded with
a thin rim of cytoplasm.

1-the secretory proteins are synthesized by the
ribosomes on the RER, and migrate to the Golgi
apparatus Convex face( cis face).
2-carbohydrate addition and other modifications are
completed in the golgi apparatus in the concave surface(
trans face).
3-The proteinaceous secretory material is concentrated
in condensing vacuoles and stored in secretory granules
and discharged by exocytosis.
Protein synthesis
By serous cell

MEANS THAT THE
SECRETORY
GRANULES
MEMBRANE IS
RECYCLED AND
THE CONTENT
EXPELLED INTO
THE LUMEN
Exocytosis:

1-The formation of mucous droplets occurs in the
same manner as was seen in the serous cells
except that this droplet has large amount of
carbohydrates due to the large size of golgi
appratus found in the mucous cell.
2-When a single droplet is discharged, its limiting
membrane fuses with the apical plasma
membrane, resulting in a single membrane
separating the droplet from the lumen.
3-This membrane may: a-fragment, or b-the
droplet may be discharged with the membrane
intact, surrounding it.
The secretion of mucous droplets

Let’s compare between the ways of mature
vesicles discharge in serous and in mucous
acini.The following figures will explain it all
What happens in a
serous cell.
What happens in a mucous
cell.
Membrane
Intact
membrane
Fragmented
with the
discharge

C-Mixed Acini
Demilune of von Ebner
(crescent of Gianuzzi)

•In mixed glands, the proportion of serous
and mucous cells vary from predominantly
serous, as in human submandibular gland,
to predominantly mucous, as in the human
major sublingual gland.
•1-Separate serous and mucous units may
exist.
•Or 2-The secretory units may be composed
of both cell types where the mucous cells
form a typical tubular portion capped at the
blind end by cap of serous cells ,known as
crescent of Giannuzzi or demilunes of von
Ebner.
•The serous secretion of the demilune cells
reaches easily the lumen through the
intercellular canaliculi.

1
2
3
1 Serous
acinus
2 Mucous
acinus
3 Mixed acini

3- Non secretory cells:
a-Myoepithelial (basket
cells)
1- Spindle shaped
2-Related to secretory
ends &intercalated duct.
3- Has 4-8 processes.
4- Attached to the
underlying cell by desmosomes.
5- Many microfilament
6- Cell organelles are perinuclear
7- Has a contractile function.
1
2
3
4
5
6
7
8
4 5
6

•It is a contractile cell located around the terminal
secretory units (more in mucous than serous acini
because the heavy mucous secretion needs more
squeezing to be expelled into the lumen) and the
intercalated duct between the basal lamina and the
basal cell membrane .
•They are stellate or spider like, with a small body filled
with flattened nucleus, and numerous long branching
processes that embrace the secretory and the duct
cells.
•By electron microscope
•Two types of filaments:
•1-Fine actin filaments (5nm thick) , oriented
longitudinally in the cell process and appear
aggregating forming dark bodies.
•2-Thicker Myosin filaments, (10 nm thick) are also
present.
•Desmosomal attachment are present between the
myoepithelial cells and the basal plasma membrane.

Function:
•1-Contraction of their process help to expel
saliva from the acini and intercalated ducts.
•2-Provides support for the parenchyma
during active secretion.

The Intralobular And Interlobular Ducts

1-Intralobular (within lobules)
a- Intercalated.
1- Small diameter.
2-Lined by simple cuboidal
epithelium
3-Central nucleus.
4- Little cytoplasm.
5- Basal RER.
6- Apical golgi complex
7- Few secretory granules
8- Numerous in watery
secreted gland ( parotid)
3
5
6
7

Functions of intercalated
ducts:1-The cells of the proximal ‫القريبة‬ ‫أو‬ ‫الدانية‬part of the duct have
secretory function.
2-They convey the secretion from the terminal secretory units
to the striated ducts.
3-Lactoferrin (a protein having an antibacterial function) has
been localized in the cells of the intercalated duct.
4-They can reabsorb protein from the lumen.
5-They may proliferate and undergo differentiation to replace
damaged or dying cells in the end pieces and striated ducts.

2-Striated duct
-lined by a single layer of
tall columnar epithelial
cells, have large
,spherical and centrally
placed nucleus and
abundant pale staining
eosinophilic cytoplasm.
-The cytoplasm at the
basal part of the cell
shows basal striation.

1-Intralobular (within lobules)
b-Striated:
1- Lined by a single layer of
columnar cells.
2- Central nucleus.
3-Esinophillic cytoplasm.
4- Prominent Basal striations due to
: a- membrane enfolding
b-numerous elongated
mitochondria
5- a-Cell organelles, b-junctional
complex & desmosomes are
present
2
a
b
4
5 a
5 b

Functions of the striated ducts:
1-They convey secretion from intercalated to
excretory duct.
2-They modify the saliva passing through them. ‫تغيرأو‬
‫تضيف‬
3-They actively reabsorb sodium and chloride ions
and secrete potassium and bicarbonate in the
primary secretion, thus the secretion is changed from
isotonic ‫اا‬‫ا‬‫متع‬ or hypertonic ‫اار‬‫ا‬‫مف‬ to a hypotonic
secretion, with low sodium and chloride and high
potassium & bicarbonate concentrations for
buffering ‫ز‬ ‫ع‬ .

Functions of the striated ducts:(cont.)
4-Lysosomes which have an antibacterial effect are localize
5-Striated ducts contain the enzyme kallikrein which
affect the water and electrolyte balance‫.التوازن‬
6-Iodine(is an essential component of various thyroid
hormone) concentration ‫تركياا‬ takes place in the
striated ducts.
7-They add Amylase enzyme(digestive)from the
serum to the saliva.
8-Cells of striated ducts have nerve and epidermal
growth factors.

3-Excretory duct and main duct
1-They are larger than
striated ducts
2- Interlobar ducts are lined
by pseudostratified
columnar epithelium with
goblet cells.
3- Main duct is lined by
stratified squamous
epithelium.
4-As the ducts increase in
size, the number of
mitochondria and
enfolding of the basal
membranes decrease.
1 2
3
Goblet cell

Functions of excretory ducts:
1-They convey the salivary secretion towards
the oral cavity.
2-They have the ability to reabsorb sodium
and secrete potassium and bicarbonate.
3-The ductal reabsorption of sodium and
chlorides exceeds the secretion of potassium
and bicarbonate leading to hypotonic saliva.

•Function:
• 4-Adding a mucoid
compound to saliva
(secreted by goblet
cells).

Excretory duct in serous gland

•-Lined with stratified squamous epithelium.
(the lining of the oral cavity)
•-Parotid duct is called Stensen duct
•-Submandibular : Wharton duct
•-Major sublingual :Bartholin duct
•-Minor sublingual : Rivinus ducts
4-Main Duct

1
DUCT
MAIN EXCRE.DUCT EXCRETORY DUCT STRIATED DUCT INTERCALATED
Modification of
primary
secretion.
Passive conduit
Sec. Granules.
Minor contribution
in secretion
Isotonic or Slightly hypertonic than
plasma.
Na+, cl- Conc. = Plasma.
K+ Conc
Na+ andPlasma .
1 – Contain Kallikrein enzyme
synthesis of glycoproteins.
2 – Presence of vesicles and lysosomes
pinocytotic activity.
3 – Basal infolding + conc. Mitochondria +
Basal portion of cells contain Na+ & K+
activated adinosine triphosphatase
(transport enzyme)
water and electrolyte transport .
Reabsorbed
from primary
secretion .
Secreted
in primary
secretion.
Secreted.Reabsorbed
Note: At increased flow rates Na+ and CL- conc.
increase, while K+ decreases., as the secretion is
in contact with the ductal epithelium for a short
time.
FUNCTIONS OF SALVARY GLAND DUCTS
Ac
inu
s

B-Oncocyte
☻Large pale-staining eosinophilic cell, loaded with
mitochondria
Found replacing the duct cells mainly in mucous glands.
☻They probably represent an age change

The Connective Tissue
Forming the Capsule , Septa and Stroma
capsule
Septa Lobe
Lobule

The Structure of the Connective Tissue
Cells Intercellular substance
■Blood vessels
■Nerves
■Lymph vessels
Fibers Ground substance
☻Collagen
& reticuline
☻ Elastic fibers
(wall of B.V.)
☻Glycosaminoglycans
☻Glycoproteins.
1-Fibroblasts
- Macrophages
- Mast cells
-Plasma cells
2-Fat cells
3-Defensive cells

•The connective tissue forms the capsule of
the gland ,septa dividing the gland into
lobes and lobules and stroma that invest all
the parenchymal portion of the gland.
•The blood vessels and nerves follow the
course of the excretory duct then the
striated ducts then the course of
intercalated ducts and form a plexus under
the striated ducts and the terminal portions.

Nerve Supply
☻The salivary glands secretion is controlled
by autonomic nervous system.
sympathetic
(adrenergic)
parasympathetic
(cholinergic)
♣ viscous saliva
less in quantity
♣ watery saliva
♥ vasoconstrictor
☻Some small mucous glands have spontaneous secretion
independently of neural control.
☻Hormones exert varying levels of control over salivary
function .
♥ vasodilator

Major Salivary Glands
Parotid
Sublingual
Submandibular

Parotid Gland
-The largest gland.
# Location:
-The superficial portion of
the gland is present in
front of the external ear.
-Its deeper portion lies
behind the ramus of the
mandible, filling the
retromandibular fossa.
-A small amount of parotid tissue
occasionally accompanies the
excretory duct forming an accessory
few mms small gland.

••♥ The gland is enveloped by a well-
formed connective tissue capsule sending
septa dividing the gland into lobes and
lobules.
•*Type of secretion:
•-The parotid gland of adult is a pure serous,
••-In infant and old ages, few mucous
secretory units may be found( mixed ).
•-
•The duct system:
••-The intercalated ducts are long and
branching.
•-The striated ducts are numerous and well
developed.
••
•-The main excretory duct (Stensen’s duct)
crosses the masseter muscle , penetrate the
buccinator muscle and open at small papilla
on the buccal mucosa opposite the maxillary
second molar.
Serous

The blood supply The nerve supply
♥ External carotid artery ♣ The parasympathetic nerve
(glossopharyngial) from the
otic ganglion and the
auriculotemporal nerve.
♣ The sympathetic nerve from
the superior cervical ganglion.

Submandibular And Sublingual Glands
Submandibular G.
Sublingual G.
Mylohyoid
muscle

☻large but smaller
than the parotid
Submandibular Salivary Gland
# Location:
- Present in the
submandibular
triangle, medial to the
mandible. It lies behind
and below the free
border of the
mylohyoid muscle with
small extension lying
above the posterior
border of the muscle.

Submandibular Salivary Gland
*Type of secretion:
Mixed predominant
serous
♥ The gland is enveloped by a well-
formed connective tissue capsule
sending septa dividing the gland
into lobes and lobules.
-The duct system:
•The intercalated ducts are shorter
than those of the parotid gland.
•The striated ducts are long.
•The main excretory duct
(Wharton’s duct) crosses over the
mylohyoid muscle and opens at
the caruncula sublingualis ( a
small papilla at the side of lingual
frenum).

♥ The facial and lingual
arteries .
♣ The parasympathetic nerve
( facial and lingual ns) from
the submandibular ganglion.

# Location:
- Lie on the superior
surface of the
mylohyoid muscle and
are separated from the
oral cavity by a thin
layer of mucosa.
Sublingual Salivary Gland
☻It is the smallest of the major salivary
glands. Composed of one major gland
and several minor glands.

Sublingual Salivary Gland
--The capsule: Is poorly
defined, but the connective tissue septa
are prominent.
-•-The major gland is
mixed predominant mucous.
•The minor glands are pure
mucous.
-The duct system:
•#The major gland: The
intercalated and striated ducts are
short.
-The main excretory duct is Bartholin’s
duct opens with or near to the
submandibular duct at the sublingual
papilla.
•#The minor salivary gland
main excretory ducts (8-12 in number)
called Rivinus ducts open
independently along the sublingual fold.
*Type of secretion:
Mixed predominant
mucous

♥ Sublingual and
submental arteries.
♣ The parasympathetic nerve
( facial and lingual ns) from
the submandibular ganglion.

Parotid G. Submandibular G. Sublingual G.

Minor Salivary Glands
☻The minor salivary glands are located beneath the
mucosal surface throughout the oral cavity.
☻The intercalated ducts are poorly developed and the
striated ducts are usually absent.
☻The glands open directly into the oral cavity by short
excretory ducts.
☻They lack a distinct capsule, instead the parenchymal
elements mix with the connective tissue of the submucosa
or the muscle fibers of the cheek ,lip or tongue.

MAJOR FEATURES OF SALIVARY GLANDS
Nerve
Sebaceous
Glands
Lymphoid
TissueFatGlandsDuctFeatureGland
Facial
Nerve
YesYesYesSerous
Stensen's
duct
Largest
major
salivary
gland
Parotid
NoneNoneNoneYes
Mucou-
Serous
Wharton's
duct
Second
largest
major
salivary
gland
Sub-
mandibular
gland
NoneNoneNoneYes
Mucou-
Serous
Bartholin's
duct,
Rivinus
ducts
Smallest
of major
salivary
glands
Sub-
lingual
gland
NoNoneNoneYes
(Tongue)
Mucous
except
for those
in
tongue
Small
Scattered
throughout
the tongue,
palate and
lip
Small
salivary
glands

Labial Glands Buccal Glands
♣ They are mixed glands.
•Consisted of mucous tubules with serous
demilunes.
•The buccal glands which lie near to
Stenson’s duct are called molar glands.

Glossopalatine Glands
♥ They are pure mucous glands.
♥ Located at the isthmus region
in the glossopalatine fold.
♥ It extends from the posterior
extension of the sublingual gland
to the glands of the soft palate
( forming the mucous ring).

Palatine Glands
♣ They are pure mucous glands.
♣ Located in the submucosa of
the posterolateral region of the
hard palate (number = 250)
♣ The submucosa of soft
palate (number = 100).
♣ The uvula (number = 12).

Lingual Glands
von Ebner Glands serous
Weber Glands mucous
Blandin Nuhn Glands
a) The anterior lingual glands.
b) The posterior lingual glands.

1-the von Ebner Gland (Pure Serous).
☻The glands are located between the muscle fibers of the
posterior part of the tongue, below the circumvallate and
foliate papillae.
☻The functions of the von Ebner salivary
glands.
1- Wash the trough of the papillae and
dissolve food particles , hence their taste
buds become ready to receive new taste
stimuli.
2- Protective function: This is provided by
antibacterial enzymes such as
peroxidase and lysozyme.
3- Digestive function, by the digestive
enzymes as amylase and lipase (lingual
lipase). The lingual lipase plays a
significant role in lipid digestion in
infants, when the pancreatic lipase is
low.

2- Weber Glands (Pure Mucous).
☻Located at the base of the tongue in association to
the lingual tonsils.
☻The ducts of the glands open on the dorsal surface of
the tongue through the lingual crypts of the lingual
tonsils.

♥ Located near the tip of the tongue.
♥ The anterior regions of the gland are
mucous, while the posterior portions
are mixed.
♥ The ducts open on the ventral surface of
the tongue near the lingual frenum.
3-Blandin Nuhn Glands

Functions of Salivary glands
1- The most important function is saliva production&
secretion.
2- Play a major role in iodine metabolism‫الغذائى‬ ‫التمثيل‬ , since
the cells of the striated ducts are engaged in iodine
concentration.
3- The parotid gland secrete a hormone called parotin
which:
a.Promotes growth of mesnchymal tissues.
b.Lowers serum calcium level.
c.Stimulates calcifications&leucocytes production in bone
marrow.

4- They secrete lots of enzymes &protein substances
as:peroxidase, lysosome, thiocyanate, sialin &amylase.
5-Salivary gland of certain animals active in produce
epidermal &nerve growth factor helping in wound healing.
6-The plasma cells in the stroma of the salivary glands form
salivary Immunogloblin IgA which has a role in the mucosal
immune mechanism of the oral cavity

Saliva Composition
☻The glandular saliva is collected from the ducts.
While the whole saliva is obtained from the oral cavity.
☻Pure glandular saliva consists of water (99%), the
remaining 1 % is made up by:
1- Inorganic ions: the major inorganic ions are Na+, K+, Cl-, and HCO3-.
The minor amounts of ions are Ca++, Mg++, HPO- -, I-, SCN- and F-.
2- Organic substances mainly represented by secretory proteins. Include
enzymes such as amylase, ribonuclease, lysozyme, peroxidase,
kallikrein, esterase and acid phosphatase. Carbohydrate, glycoprotein
and antibacterial substances.
Other organic molecules as amino-acids, urea, uric acid, various lipids
and corticosteroids.
3- Serum constituents such as albumin, blood clotting factors,
microglobulin and immunoglobulins.

* The whole saliva consists of :
1- Desquamated oral epithelial cells.
2- Leukocytes.
3- Microorganisms and their
products.
4- Fluid from the gingival sulcus.
5- Food remnants.
* The total volume of saliva secreted daily by humans is
approximately 750 ml.
☻60% is produced by the submandibular glands.
☻30% by the parotid. ☻ 3-5% from sublingual.
☻ 5-7% from the minor salivary glands.
The pH of whole saliva varies from 6.7 to about 7.4 ( the
primary buffering system of saliva is formed by HCO3-).
+ the previous components

Functions Of Saliva
1- Protective functions
1- Saliva prevents dryness of the oral tissues, and provide lubrication
for the movement of tissue against each other and protection of the
mucosa from chemical and thermal stimuli.
2- Anticariogenic function by the cleansing action of saliva and the
presence of high molecular weight glycoproteins which aggregate
microorganisms and reduce the number of bacteria in the oral cavity.
3- The buffering capacity of saliva helps to reduce the effect of
bacterial acids produced in plaque on the dissolution of tooth
minerals. And deprives the bacteria from optimal environmental
conditions (acidic pH ).

4- Certain proteins bind strongly to hydroxyapatite of the tooth
surface forming the acquired enamel pellicle. The resulting
localized super saturation of calcium and phosphate reduce the
dissolution and promotes remineralization of enamel.
5- Antibacterial factors produced by serous cells of major and minor
salivary glands.
a-Salivary peroxidase and thiocyanate , In the presence of hydrogen
peroxide (produced by oral microorganisms), establish a
bactericidal system in saliva.
b- Lysozyme, is an enzyme which hydrolyzes the polysaccharides
of bacterial walls, resulting in cell lysis.
c- Lactoferrin, an iron binding protein, may inhibit bacterial growth
by limiting the availability of iron needed by the certain bacteria.
d- By the antibodies (immunoglobulin): IgA (salivary or secretory
Ig A)
e- Histidine-rich salivary proteins have growth inhibitory and
antimicrobial activity against certain oral bacteria and fungi.

2- Taste function
a- Saliva is required to dissolve substances to be tasted and carry
them to the taste buds.
b- It also contains a protein called gusten, which is necessary for
growth and maturation of taste bud.
3-Digestive function
a- The amylase act on carbohydrate to produce glucose and maltose.
b- Lingual lipase (produced by von Ebner S.G) initiates the digestion
of dietary lipids.
4- Tissue repair
a- The saliva contains epidermal growth factor
b- Saliva also reduces the bleeding time and the blood clot formed in the
mouth ( blood+ saliva) is less solid than normal.

Age Changes In The Salivary Glands
1- The terminal portions:
-The number of secretory ends decreases by age , serous acini may be
replaced by mucous or fatty cells.
-Atrophy of a part or the whole terminal portions of a lobule and their
replacement either by fibrous or fatty tissue.
-The secretory cells decrease in height and width (the lumen becomes wider).
-The nuclei of cells show pyknosis and their cytoplasm is faintly stained with the
appearance of fatty inclusions.

Young age
Old age
Fatty degenerative change.

2- The duct system
☻ Most of intercalated ducts may disappear due to the
transformation of the cells into secretory cells, which are mostly
mucous.
☻The striations of some striated ducts may disappear.
☻The epithelial lining of the excretory ducts may undergo metaplasia.
(the epithelium changes to flattened cells).
☻Some ducts with large lumen show stagnated mucous secretion.
3- The connective tissue of the salivary glands
☻ The capsule of the parotid and submandibular salivary glands
becomes thicker and shows fatty inclusions and a large number of
chronic inflammatory cells.

Salivary glands dina+sahar audio 2

Salivary glands dina+sahar audio 2

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Salivary glands dina+sahar audio 2