The document discusses the development and histological structure of salivary glands. It begins by describing how salivary glands arise from an epithelial outgrowth from the oral epithelium that branches and canalizes to form the duct system. It then details the microscopic structure of the different cell types found in salivary glands, including serous and mucous acinar cells, and the intercalated, striated, and excretory ducts. Specifically, it focuses on the cellular features, organelles, and secretory mechanisms of each cell type. Finally, it briefly discusses the connective tissue capsule and septa that encapsulate the glands.

1. DrLaila Amin

2. Salivary
glands
Dr. Laila Amin
Lecturer of Oral Biology
DrLaila Amin

3. Development of salivary glands:
DrLaila Amin

4. Development of salivary glands:
1. Epith outgrowth:
An epithelial outgrowth of the buccal epithelium
that invades the underlying mesenchymal tissue
forming a small bulb connected to the surface by a
trailing cord of epithelium.
2. Branching:
The epithelial cord proliferates and branches
forming berry like with terminal bulbs. With
continuous branching of the cord, forming an
extensive tree-like system of bulbs.
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5. 3. Canalization:
Canalization of the epithelial cord with
formation of hollow tubes or ducts. It occurs
first at the distal end of ducts, then in the
proximal end of the main cord.
4. C.T. Capsule:
Connective tissue condensation around the
bulbs will form the capsule which surrounding
the gland and forming connective tissue septa
that divide the gland into lobules.
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6. Development of salivary glands:
• SG arise as focal thickening of oral epithelium
that grows into the underlining mesenchymal
tissue to form small bud connected to the surface
by trailing cord of epithelium
• As it grows forming epithelium bulb it clefts to
form more buds and so on as tooth developed.
Tubular lumenization done generally form distal
end of main cord to proximal end at the surface
forming the duct system. The distal end forming
the secretory end piece.

7. The salivary glands are exocrine,
merocrine glands, pour their secretion
into the oral cavity.
• The oral cavity is a moist environment by saliva
coat which is a complex fluid produced by the
salivary gland. It has important role in
maintaining the well being of the mouth.
• Patient with deficiency of salivary secretion has
difficulty in eating, speaking, swallowing and
become prone to mucosal infection and
rampant caries.

8. • There are three pair of major SG
located outside of oral cavity
encapsulated with extended ducts to
discharge their secretion.
•Also, there are uncapsulated multiple
minor SG located in submucosa
except gingiva and anterior part of
hard palate.

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10. •The secretory end pieces are differ in
size, number of cells and shape
•The shape of end piece from simple
circular or spherical to tubular outline
with continuous basement membrane
around end piece and its ducts

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13. Histological structure
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14. I-Parenchymal tissue:
• 1-secretory portion:
• A-Serous acini:
• B-Mucous acini
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15. A- Serous acini
• light microscope:
1) Pyramidal in shape
2) Lumen
3) Nucleus
4) Cytoplasm
5) Zymogen granules
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16. A- Serous acini
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17. electron microscope:
The serous cells have structural
features typical of protein
secreting cells
a) RER
b)Golgi apparatus
c) Mitochonderia
d) apical cytoplasm is filled with
electro dense secretory granules
e)Lysosome (hydrolytic enzyme)
f)Folding of the plasma mem
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18. Intracellular canaliculi
The secretory cells are
separated by
intercellular canalliculi
at its lateral walls.
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19. DrLaila Amin
Intercellular canaliculi

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21. Intercellular junctions
1. tight junctions
(zonula occludense),
2. adhering junctions
(zonula adherens),
3. desmosome
(macula adherens)
junctional
complex
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22. DrLaila Amin

23. function of juctional complex
a. Prevent the leakage of the lumen content in the
intercellular spaces.
b. Regulate the passage of materials from the
lumen to the intercellular spaces and vice
versa.
c. Hold adjacent cells together.
Also, the secretory cells attached to the basement
membrane by hemidesmosomes.
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24. Protein synthesis:
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25. cell organelles of protein synthesized
cells:
DNA transcript the nuclear RNA leaving the nucleas
carrying the code messenger RNA reaching to ribosomal
RNA to coupling the appropriate amino acids to their
proper position of newly protein.
Ultrastructure of serous cell
• Nuclear RNA
• Messenger RNA
• Ribosomal RNA

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30. .
• exocytosis
1-fusion of granule membrane with the plasma
membrane of the lumen or intercellular canalliculi
2-opening of the fused portion so the granule
membrane become continuous with plasma
membrane so
3-the granule content become exteriorized without
loss of cytoplasm
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31. DrLaila Amin

32. Mucous cells

33. • Histological structure
• Electron microscopic picture

34. B- Mucous acini:
• They are specialized for synthesis, storage and
secretion of mucins, which have a protein core
(apomucin) highly situated with sugar residue.
• Differ from serous cell glycoprotein in
Little enzymatic activity, mainly for lubrication
and protection.
Higher ratio of carbohydrate to protein.
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35. DrLaila Amin

36. light microscope:
1. Pyramidal
2. Lumen
3. Nucleus
4. Cytoplasm
5. Mucigen granules
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37. DrLaila Amin

38. electron microscope:
• The granules mucous are
pale elecrolucent, larger
and more irregular in
shape than serous
RER-Mitochonderia
Golgi complex
Junction complex
No intercellular canaliculi
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39. Electron microscope
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40. The secretion of mucous granules differ from
exocytosis of serous granules that.
• When single mucous droplet is discharged its
limiting membrane fuses with the apical plasma
membrane resulting in single membrane
separating the granule from the lumen.
• This separating membrane may then fragment
and lost with discharge of mucous OR the
mucous granule may be discharged with the
membrane intact surrounding them.
• During rapid mucous discharge, the apical
cytoplasm may not seal itself off and the entire
mass of mucous may be spilled into the lumen.
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41. Separating
membrane
Granules
discharge
with
membrane
intact
Fragment,
lost
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42. DrLaila Amin

43. mucous
serous
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44. The mucous end piece have serous cells associated with
them in the form of demilunes or crescent called serous
demilion or crescent of Giganzi.
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50. Arrangement of cells in the terminal secretory unitsArrangement of cells in the terminal secretory units

51. difference Serous acini Mucous acini
1- size Small larger
2-lumen narrow wider
3- cells High pyramidal Low pyramidal
4-cytoplasm Basophilic (RNA) Empty, vaculated
5- granules zymogen mucigen
6-nucleus Spherical at basal
side
Flattened, pressed
basally
7-crescent demillion absent present
8- canaliculi present absent
9- L M
10- E M
11- intercalated duct tall short
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52. DrLaila Amin

54. Mixed salivary gland

58. Ducts

59. 2- Duct system:
• 1-Intercalated Ducts:
• 2-Striated Duct:
• 3-excretory Duct:
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60. 1-Intercalated Ducts:
• The primary saliva produced by the
acini passes first through the
intercalated ducts
• They are prominent in salivary gland
having watery secretions so they are
long and branching in parotid gland,
somewhat shorter in submandibular
gland and poorly developed in
sublingual gland.
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61. DrLaila Amin

62. Light microscope:
1. simple cuboidal epithelium
2. large centrally nucleus
3. little cytoplasm.
4. myoepithelial cell bodies and their processes are
located along the basal surface of the duct.
5. Their overall diameter is smaller than that of the
end piece
6. Larger lumen
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63. Electron microscope
• small amount of RER
• small Golgi apparatus apically to the nucleus
• few small secretory granules may be found in
their proximal end (near to secretory units).
• The myoepithelial cells bodies and their
processes are attached by desmosomes to ducts
cells
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64. Electron microscope
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65. Functions:
1. Collect the primary saliva formed by terminal secretory
units
2. Convey the secretion from the terminal secretory units to
the striated ducts.
3. Reserve of undifferentiated cells which proliferate and
undergo differentiation to replaced damaged or dying cells.
4. Reabsorbing proteins from the lumen by endocytosis with
the striated ducts
5. Macromolecular components stored in their secretory
granules include: lysozyme and lactoferrin (antibacterial
proteins).
6. Modify the saliva through secretory and reabsorptive
processes.
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67. DrLaila Amin

68. DrLaila Amin
Intercalated duct

69. 2- Striated Duct:
• It constitutes the largest portions of ducts
system and the main ductal component
located within the lobules of the gland
(intralobular duct system).
• They receive primary saliva collected by
intercalated ducts.
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71. Light microscope:
1. single layer of tall columnar epithelial cells
2. large spherical centrally located nuclei abundant
pale staining acidophilic cytoplasm.
3. The cytoplasm show faint radially oriented lines or
striations in basal end of cells perpendicular to
basal surface so the duct called striated.
4. The overall diameter of duct is greater than that of
secretory end piece and the lumen is larger than
those of secretory end pieces and intercalated
ducts.
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73. DrLaila Amin

74. Electron microscope
1. The striations correspond to multiple enfoldings of the
plasma membrane at the base of the cell.
2. Vertically aligned mitochondria between the enfoldings,(
large surface area, high levels of energy, active
transport).
3. Few short RER and small Golgi apparatus (perinuclear
cytoplasm)
4. small secretory granules on the luminal side
5. Several lysosomes, numerous small peroxisomes and
deposits of glycogen frequently are present in the
perinuclear cytoplasm
6. adjacent cells are joined by well-developed tight
junctions and junctional complex but lack gap junction.
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75. DrLaila Amin

76. Function:
A . The highly infolded basal membrane greatly
increase the surface area available for transport
processes.
B . The concentration of mitochondria near
these membranes provides abundant supply of
high energy compounds.
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77. • Electrolyte reabsorption and secretion by
striated duct is regulated by autonomic
nervous system and by mineralocorticoids
produced by adrenal cortex.
D)Lysosome which have an antibacterial effects.
• Striated ducts contain the enzyme kallikrin
which affect the water and electrolyte
balance.
E)Amylase enzyme is added from the serum to
the saliva by the cells of the striated ducts.
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78. C) . Modify the primary saliva by
1) 1ry saliva (acini, intercalated
ducts)
isotonic {high Na+ ,low K+}.
1) Striated ducts (massive
folding) reflect Na+-pumping
2) Na+ diffuse into cells from
luminal fluids at the same
time active transport of K+
occur in opposite direction.
3) Hco3
- is also actively secreted.
hypotonic fluid {low Na+,Cl-}
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79. 1ry saliva
isotonic
↑Na-↓K
Na
K
H
co
3Hypotonic
↓Na-↓Cl
Striated
duct
cl
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80. DrLaila Amin

84. 3- Excretory Ducts:
• When striated ducts
leave the glandular
lobules, they enter the
interlobular connective
tissue and become
excretory ducts, so they
have extralobular or
interlobular location.
• They are larger in
diameter than striated
ducts.
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85. Light microscope:
• Near striated ducts:
it is lined by pseudostratified epithelium with
columnar cells extending, small basal cells that
sit on the basal lamina but do not reach the
lumen,
• Near the oral cavity:
the epithelium gradually changes to stratified
squamous epithelium that merge with the
epithelium of oral cavity at duct orifice.
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86. DrLaila Amin
intralobular Near the oral
cavity:

87. DrLaila Amin

88. Electron microscope:
1. Numerous mitochondria (less than striated duct cells
2. as the ducts increase in size, the number of
mitochondria and extent of striation decrease.
3. few, if any apical secretory granules.
4. The basal cells have numerous bundles of
intermediate filaments (tonofilaments) and are
attached to the basal lamina by promonent
hemidesmosomes. In some instances basal cells may
contain abundant actin filaments and have elongated
processes similar to myoepithelial cells.
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89. 5. Other cells with pale cytoplasm and dense
nuclear chromatin
a) Lymphocytes and macrophages.
b) Dentritic cells or antigen presenting cells,
c) Tuft (caveolated or brush) cells, with long
stiff microvilli and apical vesicles are thought
to be receptor cells to some type
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90. Functions:
1) They convey the salivary secretion towards
the oral cavity.
2) They have the ability to reabsorb sodium and
secrete potassium and bicarbonate.
3) They are also capable of modifying saliva
through process of electrolyte reabsorption
and secretion, perhaps also by adding
mucoid compound.
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94. The connective tissue
• includes a surrounding capsule, variably
developed, that demarcates the gland from
adjacent structures.
• Septa that extend inward from the capsule
divide the gland into lobes and lobules and
• carry the blood vessels and nerves that supply
the parenchymal components and the
excretory ducts that convey saliva to the oral
cavity
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95. DrLaila Amin

96. DrLaila Amin

100. • Striated ducts
–Ultra structure of the striated ducts

104. Excretory ducts

107. Oncocytes

108. Myo-epithelial cells

109. Myoepithelial cell
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113. Myoepithelial
cell
contractile cells located around the terminal
secretory portion and the intercalated ducts.
()the basal lamina and the plasma membrane
of parenchymal cells, joined to cells by
desmosomes. DrLaila Amin

114. Light Microscope:
• stellate or spider like in shape with a small body
filled mostly with flattened nucleus.
• numerous long branching processes that embrace
the secretory and duct cells. Their process are filled
with filaments of actin and myosin
• Around acini (gutter)- around intercalated duct
• H&E stain (non), special stain as adenosine
triphosphate in human and alkaline phosphatase in
animal.
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115. Electron microscope:
a) nucleus is flattened
b) cytoplasmic organelles (perinuclear area).
c) numerous cell processes present in the surface
of acini and duct( L.T actin).DrLaila Amin

116. • Histological structure
• Ultra structure of the myo-
epithelial cell

119. Functions:
• 1- Contractile functions to expel secretion of
saliva from the acini and duct because
• -similar to smooth muscles
a. imunoflurescent studies suggest the presence
of actin and myosin filament.
b. measurement of ductal pressure after
myoepithelial cells stimulation suggest it have a
contractile functions.
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120. • 2-it support the secretory end piece during
active secretion of saliva.
• 3-it produce number of proteins that have
tumor suppressor activity , which provide a
barrier against invasive of epithelial
neoplasms.
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121. DrLaila Amin

122. Classification of
salivary glands
I-Size
II-
Location
III-
Secretion
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123. According to size:-
1- Major salivary glands
1. Parotid gland
2. Submandibular glands
3. Sublingual glands
2- Minor salivary glands
1. Minor sublingual glands
2. Labial and Buccal glands
3. Palatine glands
4. Glossopalatine glands
5. Retromolar gland
6. Lingual glands( Blandin Nuhn, Von Ebner, Weber)
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124. According to location:-
1-Oral vestibule:
1) Labial glands
2) Buccal glands
3) Parotid gland
2- Oral cavity proper:
1) Submandibular gland.
2) Sublingual gland
3) Palatine glands
4) Glossopalatine glands
5) Lingual glands( Blandin Nuhn, Weber and Von Ebner).
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125. According to nature of secretion:-
Pure serous
Parotid gland of adult
Von Ebner
Pure mucous
Minor sublingual glands
Labial and Buccal glands
Anterior portion of
anterior lingual glands
(Blandin Nuhn)
Mucous ring
Mixed
glands:
Predominantly Serous:-
Submandibular gland
Parotid gland of infants
and old aged
Predominantly Mucous:-
Major Sublingual gland
Posterior portion of the
anterior lingual gland (Blandin
Nuhn)
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126. Major Salivary Glands
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127. I- parotid Gland
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128. A -Location:
Superficial part: in front of the external ear, associated
with the peripheral branches of the facial nerve.
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129. Deep part:
fills the retromandibular fossa behind the
ramus of the mandible.DrLaila Amin

130. DrLaila Amin

131. B-Structure
• Adult gland: purely serous.
• In infants: may have few
mucous acini. DrLaila Amin

132. C- weight
• 14-28 gm
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133. D- ducts
• Excretory duct: Stenson’s duct runs forward
across the masseter and then turns inward at
the anterior border of the muscle to open in
front of the maxillary second molar.
• Striated ducts: numerous and well developed.
• Intercalated ducts: long.
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134. Masseter
msc
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135. E-Capsule
• Well formed connective tissue capsule.
• Fat cells are found in the C.T. septa and
increase in number with age replacing parts of
the gland.
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136. F- Nerve supply
• Sympathetic: superior
cervical ganglia
• Parasympathetic:
glossopharyngeal
(auriculotemporal
nerve).
• Sensory: from the
trigeminal nerve.
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137. DrLaila Amin

138. G- Blood supply
exrenal carotid
artery
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139. DrLaila Amin

140. A- location
• In the
submandibular
triangle behind
and below the
free margin of
the mylohyoid
muscle.
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141. DrLaila Amin

142. B- structure
• Mixed predominantly serous with some mucous
capped acini.
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143. C- weight:10-15 gm
D- capsule: well formed
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144. E- Ducts
• Excretory duct: Wharton’s duct runs forward
above the mylohyoid muscle and opens at a
small papilla at the side of the lingual frenum
called caruncula sublingualis.
• Striated ducts: are longer
• Intercalated ducts: are relatively shorter than
the parotid.
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145. DrLaila Amin

146. Caruncula sublingualis.
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147. Nerve supply
• Sympathatic: as parotid
• Parasympathetic: From the facial.
• Preganglionic fibers of chorda tympani
postganglionic fibers reach the gland through
the lingual nerve.
• Sensory: the same as the parotid.
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148. Blood supply
facial, lingual arteries
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149. III-Sublingual gland
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150. A- Location
• Between the floor of the mouth and the
mylohyoid muscle.
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151. B- STRUCTURE
• Mixed predominantly mucous with some
serous demilunes.
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152. Ducts
• Excretory duct: Bartholin’s duct opens with or
near the submandibular duct in the sublingual
fold.
• 8-12 ducts called ducts of Rivinus open
independently in the sublingual fold.
• Striated ducts, Intercalated ducts : poorly
developed
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153. DrLaila Amin

154. DrLaila Amin

155. • Capsule: poorly
developed
• Nerve supply
• As submandibular
gland
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156. 1-location
Parotid Submandibular Sublingual
2- structure Adult: purely serous.
infants: serous, few
mucous acini.
Mixed
predominantly serous
with some mucous
capped acini.
Mixed predominantly
mucous with some
serous demilunes.
 Pure serous acini
are rare or
absent.
3-Weight 14-28 g
30% of secreted
saliva
10-15g
60%
2g
5%
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157. 4-Ducts Stenson’s
duct
Wharton’s duct Bartholin’s duct
8-12 ducts called ducts
of Rivinus open
independently in the
sublingual fold.
Long. Shorter than the
parotid.
Poorly developed
numerous
and well
developed.
longer poorly developed
and may lack the
striated
appearance
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158. 5- Capsule Well formed .
Fat cells
Well formed Poorly defined
6- innervation
superior
Glossopharyngeal
Nerve
(auriculotemporal)
cervical
Facial Nerve
(the lingual nerve)
ganglia
As Submandibular
Sympathetic
Parasympathetic
Motor
the trigeminal nervesensory
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159. Parotid Submandibul
ar
Sublingual
Blood supply
external carotid
artery
facial and lingual
arteries
sublingual and
submental arteries.
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160. DrLaila Amin

161. Minor salivary gland
Palatin
gland
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163. DrLaila Amin

164. Lingual gland
Von-Ebnor
S.G
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165. Labial glands
Buccal gland
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166. DrLaila Amin

167. • at the isthmus region
between the oral cavity
and the pharynx which
include:
1. Weber gland
2. palatine
3. glossopalatine glands.
The mucous
ring
Waldier Ring
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168. Saliva
saliva
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169. DrLaila Amin

170. • Quantity:
• Stimulation:
• Distribution:
• Consistency:
• PH:
Saliva
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171. Structure:
99% of water 1%
Inorganic
ions:
Organic substances:
Enzyme-Igs-mucin
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173. DrLaila Amin

174. 1. Protection
2. Buffering
3. Digestive
4. Taste
5. Tissue repair
6. Tooth integrity
7. antimicrobial
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175. 1.Protection
– lubricant (glycoprotein)
– barrier against noxious stimuli; microbial toxins
and minor traumas
– washing non-adherent and acellular debris
– formation of salivary pellicle
• calcium-binding proteins: tooth protection; plaque
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176. 2-Buffering
• (phosphate ions and bicarbonate)
– bacteria require specific pH conditions
– plaque microorganisms produce acids from sugars
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177. 3-Digestion
– neutralizes esophageal contents
– dilutes gastric chyme
– forms food bolus
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178. 4- Antimicrobial
– lysozyme hydrolyzes cell walls of some bacteria
– lactoferrin binds free iron and deprives bacteria of
this essential element
– IgA agglutinates microorganisms
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179. 5-Maintenance of tooth integrity
– calcium and phosphate ions
• ionic exchange with tooth surface
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180. 6-Tissue repair
– bleeding time of oral tissues shorter than other
tissues
– resulting clot less solid than normal
– remineralization
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181. 7-Taste
– solubilizing of food substances that can be sensed
by receptors
– trophic effect on receptors
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182. Age changes
• By age generalized loss of salivary gland
parenchymal tissue occurs and this loss may be
replaced by adipose tissue.
• Decreased production of saliva is noted.
• Atrophy or degeneration of part or whole
terminal portion may occur with replacement
with fibrous tissue causing fibrosis.
• Accumulation of lymphocytes within the stroma
of the salivary glands.
• Secretory acini decrease in number and secretory
cells decrease in height and width.
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183. Oncocytes
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184. http://www.edewcate.com/Inner.aspx?FileName=%7B5418AFC1-96B4-4DD1-8FC5-
73FD651DC75B%7D.flv

185. Clinical Considerations
• Xerostomia(dry mouth):
Reduction in the amount of secreted saliva may lead to sensation of oral dryness.
Causes:
1) It occurs mostly as a side effect of other medications.
2) After radiation therapy to the head and neck region.
3) In auto-immune diseases as Sjogren syndrome.
Effects:
 Speech, eating and swallowing become difficult and painful.
 Teeth become highly susceptible to caries especially at the gingival margins.
Treatment:
 artificial saliva.
 pathomimetic drugs as pilocarpine to increase salivary flow.
 Stem cell therapy can alleviate the condition of the gland.
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186. Diseases:-
1- viruses such as cytomegalovirus, Epstein-Barr and human
herpes viruses infect and replicate within the salivary glands and
are shed into the saliva.
2- bacterial infections.
3- Ductal obstruction may be caused by formation of stones
(sialolith) especially in the submandibular glands
4- Severing of the duct of minor salivary glands by trauma.
5- Salivary glands may be affected by endocrine diseases like
diabetes
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187. Thank you
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188. DrLaila Amin