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SALIVARY GLANDS.pptx
1. Contents
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Introduction
Composition of saliva
Functions of saliva
Anatomy of salivary glands
Development
Structure
Formation and secretion of saliva
Ductal modification of saliva
Histology of the major salivary glands
Histology of the minor salivary glands
Age changes
Clinical considerations
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2. Introduction
• The oral cavity is kept moist by a film of fluid called saliva that
coats the teeth and the mucosa.
• Saliva is a complex fluid, produced by the salivary glands, the
most important function of which is to maintain the well-
being of mouth.
• Individuals with a deficiency of salivary secretion experience
difficulty in eating, speaking, and swallowing and become
prone to mucosal infections and rampant caries.
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3. • In human beings, three pairs of major salivary glands- the
parotid, submandibular, and sublingual.
• They are located outside the oral cavity, with extended duct
systems through which the gland secretions reach the mouth.
• Numerous smaller minor salivary glands are located in various
parts of the oral cavity- the labial, lingual palatal, buccal,
glossopalatine, and retromolar glands- typically located in the
submucosal layer, with short duct openings directly onto the
mucosal surface.
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4. Saliva
• Is a clear, slightly acidic, mucoserous secretion.
• The whole saliva is a complex mixture of fluids, with
contributions from major and minor salivary glands and the
gingival crevicular fluid, containing a high population of
normal oral bacteria, desquamated epithelial cells and
transient residues of food or drink, following their ingestion.
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5. Composition of saliva
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Parameter Characteristics
Volume 600-1000ml/day
Electrolytes Na+, K+, Cl-, Ca2+, Mg2+and F-
Secretory
proteins/peptides
Amylase, proline-rich proteins, mucins, histatin, cystatin,
peroxidase, lysozyme, lactoferrin and defensis.
Immunoglobulins Secretory immunoglobulins A, immunoglobulins G and M
Small organic Glucose, amino acids, urea, uric acid, and lipid molecules
Other components Epidermal growth factor, insulin, cyclic adenosine
monophosphate-binding proteins, and serum albumin
6. Functions of saliva
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Function Effect Active constituents
Protection Clearance Water
Lubrication Mucins, glycoproteins
Thermal or chemical
insulation
Mucins
Tannin binding Basic proline-rich
proteins, histatins
Buffering pH maintenance Bicarbonate, phosphate,
basic proteins, urea,
ammonia
Neutralization of acids
8. 4/30/2015 9
Function Effect Active constituents
Digestion Starch, triglyceride
digestion
Amylase, lipase
Taste Solution of molecules Water and lipocalins
Maintenance of taste
buds
Epidermal growth factor
and carbonic anhydrase
VI
9. • Gland- An organized aggregation of cells functioning as a
secretory or excretory organ.
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10. Classification of Glands
• Glands can be divided into two groups:
1. Endocrineglands- are glands that
secrete their products onto a surface
rather than through a duct.
• e.g.- Adrenal gland, Pituitary gland.
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11. 2) Exocrine glands
- These glands secrete their products via
a duct. e.g.- Salivary glands. It can be divided into three
groups:-
a) Merocrine gland
e.g.-Mucous and Serous
glands
b) Apocrine gland
e.g.-Sweat glands
c) Holocrine gland
e.g.-Sebaceous glands
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12. Classification Of Salivary Glands
1) ACCORDING TO SIZE:
A) MAJOR B) MINOR
Parotid Glands of Lips,
Submandibular Cheeks , Hard
Sublingual Palate, Soft palate,
Von Ebners and
Blandin & Nuhn.
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14. 2) ACCORDING TO BRANCHING OF DUCTS:
A) Compound
- Major glands
B) Simple
- Minor glands
3) ACCORDING TO SECRETION:
SEROUS MUCOUS MIXED
a)Parotid a)Palatine a)Submandibular
b)Von-ebner b)Post. lingual b)Sublingual
c) Glossopalatine c)Buccal
d)Labial.
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16. Parotid gland
• Is the largest
• Weight – 15gms
• Is situated below the External acoustic meatus, b/w the ramus
of the mandible and the sternocleidomastoid and overlaps
them.
• Secretion of parotid gland is serous.
• Anteriorly , the gland overlaps the masseter muscle. A part of
this forward extension is often detached – Accessory Parotid
which lies b/w the zygomatic arch and the parotid duct.
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18. Parotid Capsule
• The investing layer of deep cervical fascia forms the capsule
for the gland.
• The fascia splits to enclose the gland.
• Superficial lamina – thick & adherent to the gland.
• Deep lamina – thin – attached to the styloid process, the
mandible and tympanic plate.
• A portion of deep lamina, extending between the styloid
process and the mandible – thickened to form
Stylomandibular Ligament –separates the Parotid gland from
the Submandibular salivary gland.
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19. External Features
• The glands has four surfaces
a) Superior
b) Superficial
c) Antero-medial
d) Postero-medial
• The surfaces are separated by three borders.
a) Anterior
b) Posterior
c) Medial
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20. Relations
1. Superior surface related to
External acoustic meatus
Superficial temporal vessels
Posterior surface of TMJ
Auriculotemporal nerve
2. Superficial surface (largest)
a) Skin
b) Superficial fascia
i. Great auricular nerve
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21. ii) Pre-auricular lymph node
iii) Posterior fibers of platysma
c) Parotid fascia
d) Deep parotid lymph nodes
3. Anteromedial surface
o Masseter
o Lateral surface of TMJ
o Posterior border of the mandible
o Medial pterygoid
o Terminal branches of facial nerve
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24. 5. Anterior border :
– Separates the superficial surface from the
Anteromedial surface
– Extends from –anterior part of the superior surface
to the apex
– Structures emerging:
Parotid duct
Terminal branches of the facial nerve
Transverse facial vessels
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26. 6. Posterior border :
– Separated the superficial surface from the
posteromedial surface
– Overlaps the sternomastoid.
7. Medial border :
– Separates the Anteromedial surface from the
posteromedial surface.
– Related to the lateral wall of pharynx.
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28. 2. Veins
• Retromandibular vein
divides into:
1. Posterior division drains into
external jugular vein
2. Anterior division drains into
common facial vein
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29. 3. Nerves
• Terminal branches of facial
nerve
a) Temporal
b) Zygomatic
c) Buccal
d) Mandibular
e) cervical
• Parotid lymph nodes
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30. Nerve Supply:
• Parasympathetic nerves are secretomotor.
-Reach the gland through the auriculotemporal nerve.
•
•
Sensory – auriculotemporal nerve.
Sympathetic nerves are vasomotor
–Derived from the plexus around the external carotid
artery
Lymphatic Drainage
• Upper deep cervical nodes
Blood Supply :
•
•
ECA
Veins – drain into external jugular vein
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31. Parotid Duct
• Stensen’s duct-5cm long
• Emerges from the substance of the gland to course anteriorly
until it reaches the anterior border of the masseter muscle at
a point of the upper and middle third.
• When it crosses the masseter muscle it receives the duct of
the accessory lobe.
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32. • Around the border of the masseter muscle-turns sharply
medially, often embedded in the furrow of the protruding
buccal fat pad.
• In its medial course ,the duct reaches the outer surface of the
buccinator muscle, where it
direction anteriorly and medially.
perforates in the oblique
• Then runs for a short distance obliquely forward, between the
buccinator and the mucous membrane –opens on the oral
surface of the cheek
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33. Submandibular gland
• Situated in the anterior part of the Digastric triangle
• Size that of a walnut
• Is J-shaped
• Secretion of submandibular gland is both serous and mucous.
• Divided by the posterior border of the Mylohyoid Muscle into
1. Larger part superficial to the muscle
• Covers the inferior surface of the gland
• Attached to the base of the mandible
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34. 2. Small part lying deep to the muscle
• Covers the medial surface of the gland
• Attached to the mylohyoid line of the mandible
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36. Superficial part:
– Fills the digastric triangle
– It has
a. Inferior surface-covered by-
Skin
Platysma
Cervical branch of facial nerve
Deep fascia
Facial vein
Submandibular lymph nodes.
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37. b. Lateral surface
• Submandibular fossa on the mandible
• Facial artery
c. Medial surface divided into
a) Anterior part – related to the
– Mylohyoid muscle
– Nerve
– Vessels
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39. Submandibular Duct
• Called “WHARTONS” duct
• 5 cm long
• Emerges at the anterior end of deep part of the gland
• Runs forwards on the hyoglossus ,between the lingual and
the hypoglossal nerves
• Opens in the floor of the mouth on the summit of the
sublingual papilla, at the side of the frenum of the tongue
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41. BLOOD SUPPLY AND LYMPHATIC DRAINAGE :
• Facial artery
• Veins drain into common facial vein or lingual vein
• Lymph passes into the Submandibular lymph nodes
NERVE SUPPLY :
• Supplied by branches from
• Submandibular ganglion
• These convey
– Secretomotor fibers
– Sensory fibers from lingual nerve
– Vasomotor sympathetic fibers from facial artery.
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42. Sublingual gland
• Is the smallest
• Almond shaped
• 3-4gm weight
• Secretion of sublingual gland is both serous and mucous.
• Lies above the mylohyoid, below the mucosa of the floor of
the mouth
• Medial to the sublingual fossa
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43. • Lateral to genioglossus
• About 15 ducts emerge from
the gland –
Called ducts of rivinus
BLOOD SUPPLY:
• Lingual and submental
arteries.
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44. Minor Salivary Glands
• Scattered & distributed in gaps beneath the epithelium having
small & narrow ducts
• Present almost on all parts of the oral cavity
• Absence of separate capsule on the glands
• They can be divided into:
a)
b)
c)
Labial & buccal glands
Palatine glands
Glands of tongue-anterior glands
-posterior glands
-Von ebners’ glands
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46. LABIAL & BUCCAL GLANDS
• Present under epithelium of lips & cheeks
• Mixed in nature
• Intercalated duct are variable in length.
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47. PALATINE GLANDS
• Present at glandular region of hard palate i.e. posterolateral
part of hard palate.
• Pure mucous gland
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48. GLANDS OF TONGUE
Anterior Gland:
• Near apex of tongue anterior lingual gland are present. These
are glands of Blandin & Nuhn.
• Mucous in nature
• Ducts of these gland open on ventral surface of tongue near
lingual frenum.
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49. Posterior Glands:
• Present on posterior part of tongue near suclcus terminalis
• Mucous in nature
• Ducts open at dorsal surface of tongue
von Ebner’s gland:
• Serous gland
• Opening through vallate papilla.
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50. Development Of Salivary Glands
Development of salivary glands occurs in six stages:
1) Bud Formation
2) Formation And Growth Of Epithelial
Cords
3) Branching Of Cords
4) Dichotomous Branching
5) Canalization
6) Cytodifferentation.
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51. Stage 1-Bud Formation
• Underlying mesenchyme
induces the overlying
epithelium to proliferate.
The epithelium thus forms
a bud.
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52. Stage 2 -Formation And Growth Of
Epithelial Cord
• The epithelial bud proliferates
to form a solid cord of cells.
• The underlying mesenchymal
condensation
proliferates.
also
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53. Stage 3-Branching Of Cords
• The epithelial cord
and
proliferates rapidly
branches into terminal bulbs.
This stage donates the
initiation of branching.
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54. Stage 4-Dichotomous Branching
• The terminal end branches
extensively
bulbs.
forms numerous
• The connective tissue below
the epithelial cord forms a
the
capsule and surrounds
entire glandular structure.
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55. Stage 5-Canalization
• Extensive branching of the duct
structure
connective
continues
and growth
tissue
of
septa
at
development.
this stage of
• First in distal ends of main cord
& in branch cords then in
proximal part of main cord &
finally in central portion of main
cord
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56. Stage 6- Cytodifferentation
• At last there is
cytodifferentation of the
functional acini
intercalated ducts.
and
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57. Development Of Salivary Gland In Intrauterine
Life
• ParotidGland- 4
th
Week of intrauterine life
• SubmandibularGland- 6
th
Week of intrauterine life
• SublingualGland- 8
th
week of intrauterine life
• Minorglands- 12
th
week of intrauterine life.
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58. Molecular analysis
• The mechanism(s) by which tissues interact include
"instructive" interactions in which the changes induced in the
responding tissue are totally new and would not have
occurred unless the specific interaction had taken place.
• The changes associated with the determination (the
commitment to a specific function) of a cell's developmental
pathway are usually induced by an "instructive“ type of
interactive event.
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59. • Other types of heterotypic interactions are "permissive" in
nature in that they facilitate the full expression of tissue
characteristics that have already been determined.
• Thus, "instructive" interactions tend to restrict the cell's
developmental options, while 'permissive'' interactions
regulate or amplify the degree of expression or stabilization of
the remaining developmental potential of the cell.
• Developmental, heterotypic tissue interactions between the
mesenchyme and the epithelium play a significant role in
inducing and controlling both the morphogenesis and the
cytodifferentiation of developing salivary glands.
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60. Epithelial-mesenchymal interactions in salivary gland
morphogenesis
• Epithelial mesenchymal interactions between the epithelium
of the salivary gland anlage and its mesenchymal capsule
directly control the development of the gland's characteristic
branching pattern.
• The mesenchyme appears to exercise control over the
behavior of the salivary epithelium through the selective
production and destruction of specific extracellular matrix
molecules
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61. • These extracellular matrix molecules are deposited in and
near the basement membrane, which serves as the interface
between the epithelial cells and their investing mesenchymal
capsule.
• It consists of a complex mixture of molecules, including
proteoglycans (heparan sulfate, chondroitin sulfate), laminin,
type IV collagen, fibronectin, and entactin .
• The dynamic nature of the molecular composition of the
basement membrane permits the structure to induce and
maintain developmental changes in the encased epithelium.
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62. Role of collagen
• Collagen, produced by the capsular mesenchyme, was the
important molecule in regulating and maintaining
branching pattern of the submandibular gland.
the
• Collagen serves as a stabilizing component that inhibits cell
growth in specific areas of the growing salivary gland
rudiment, while other areas are devoid of collagen and thus
able to grow.
• The synthesis and deposition of both types I and III collagen
appear to be
morphogenesis.
required for salivary gland branching
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63. • Types I and III collagen appear to prevent hyaluronidases and
other enzymes from digesting the basement membrane by
binding with heparan sulfate proteoglycan and other
basement membrane components to stabilize the basal
lamina.
• Deposition of type III collagen at the cleft or branch point
areas seems to play a key role in regulating both assembly of
basal lamina components and stabilizing these points so that
branching may go forward.
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64. Role of fibronectin
• Fibronectin is expressed by the salivary gland epithelium, but
also that it was expressed at much higher levels in cleft
compared to bud epithelium.
• Fibronectin and fibronectin receptor function are needed for
cleft formation, the initial stage of salivary gland branching
morphogenesis.
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65. Other extracellular molecules
• Laminin γ2- it is expressed highly in the epithelial end bud
regions of salivary glands.
• It might regulate the development of embryonic epithelium in
various organs by stimulating cell motility ; in the salivary
gland, it might be involved in outward bud expansion.
• Extracellular matrix proteins undergo degradation
turnover by matrix metalloproteinases (MMPs).
and
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66. Structure of Salivary Glands
• Is architecturally TUBULOACINAR
• Consists mainly of:
1.Terminal secretory units- Acini
2. Ductal system
3. Myoepithelial cells
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67. 4/30/2015 68
• General structure of salivary
gland is compared with bunch
of grapes with grapes
represent the secretory acini
while stalk represent ductal
system.
68. • Acini
• The basic functional unit of salivary gland is the terminal
secretory unit called Acini.
• The cells in the acini rest on basement membrane and are
arranged in single layer.
• The central lumen of each acini may have a star shaped
morphology .
• The secretory terminal unit in serous acini is generally made
up of 8-12 serous surrounding a central lumen.
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70. • Serous cells
• Cells are pyramidal in shape.
• Base resting on basal lamina & apex towards lumen
• Nucleus spherical in shape & located basal third of pyramid.
• Accumulation of secretory granules in apical cytoplasm
• That have many protein granules in their cytoplasm which
secrete polysaccharides.
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74. • These granules increase in density as their content condensed
& forming mature secretory granules.
• This cells joined by each
intercellular junction such as:
other or mucous gland by
1. Tight junctions (zonula occludens)-->fusion of outer cell
layer
2. Intermediate junction (zonula adherens)-->intercellular
communication
3. Desmosomes-->firm adhesion
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76. • Mucous cells
• Specialized for synthesis, storage, and secretion of secretory
proteins. Mucous secretion differs from secretion of serous in
two respects:
a) have little or no enzymatic activity.
b) ratio of carbohydrate to protein is greater.
• In cross section these tubules appear as round profile with
mucous cell surrounding central lumen
• In electron microscope mucous secretory appear swollen,
their membrane are disrupted & they often fused with one
another.
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78. • Mucous end pieces in major salivary glands & some minor
glands have serous cell associated with them in form of
crescent covering the mucosa cells at end of tubules.
• Accumulation of
product
apical cytoplasm of large
compress
amount
nucleus
of
&
secretory (mucous) which
endoplasmic reticulum against basal cell membrane.
• Have large golgi complex located mainly basal to mass of
secretory granules.
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81. • Ductal system
• Comprises a varied network of ducts characterized by
progressively narrow membranes.
• The network contains 3 classes of ducts:
a. Intercalated ducts
b. Striated ducts
c. Terminal excretory ducts
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82. INTERCALATED DUCTS
– The secretion of the terminal end piece first pass
through the intercalated ducts.
– Are of small diameter
– Lined by short cuboidal cells with centrally placed nucleus
and little cytoplasm
– Contains RER which is situated basally and golgi complex
situated apically
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83. • Secretory granules are occasionally found.
• Prominent in glands with watery secretion
• Hence occur in parotid gland
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85. • Striated Ducts
• Receive saliva from intercalated ducts.
• The intercalated ducts pass into the striated ducts.
• Lined by columnar cells
• Have centrally placed nucleus and intense eosinophilic
cytoplasm.
• Characteristic features –
Prominent striations at the basal ends of the cell
4/30/2015 86
86. • Around the nucleus a few RER and golgi complex are found.
• Luminal surface is characterized by short, stubby microvilli
• Adjacent cells are united by junctional complexes and
desmosomal attachments
• Are always surrounded by no. of longitudinally oriented blood
vessels.
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88. • Excretory ducts
• The salivary fluid is secreted into oral cavity through the
terminal excretory ducts.
• Near the striated ducts it is lined by a pseudo stratified
epithelium consisting on tall, columnar cells.
• After passing through the striated ducts ,the salivary fluid is
secreted through the terminal excretory ducts.
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89. • As the terminal secretory ducts approach the oral cavity, their
epithelium changes to true stratified epithelium merging with
that of the oral cavity.
4/30/2015 90
90. • Myoepethelial cells
• Stellate or spider-like
perinuclear cytoplasm.
with flattened nucleus, scanty
• Their appearance is reminiscent of a basket cradling the
secretory unit, hence the term BASKET CELL.
• These cells are contractile in nature like muscle. These cells
contract causing pulsation & release of secretory product
from end cell.
• These are also end piece cells but non secretory in nature.
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91. • These cells have octopus like structure having cell body
present in intercalated duct region with processes extending
onto parts of secretory end piece.
• In body of cell small flattened nucleus is present.
• From cell body 4 to 8 processes radiate.
• b/w myoepithelial
attachment present.
cells & secretary cells desmosomal
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92. • Cytoplasmic organism present in perinuclear region.
• Cells act as support for secretory cells by preventing their over
distention, because secretory product accumulate within their
cytoplasm.
• These cells also contract & widen the diameter of intercalated
ducts. Thus they lower or increase their resistance to flow.
4/30/2015 93
94. • Primary saliva
– Serous and mucous cells
– Intercalated ducts
• Modified saliva
– Striated and terminal ducts
4/30/2015 95
• Production And Secretion Of Saliva
95. • Saliva is formed in the secretory end pieces and consists of 2
components:
a) Macromolecular components:
Derived from the Secretory and synthetic activity
of acinar cells.
b) Fluid component:
derived from blood
4/30/2015 96
96. REGULATION OF SALIVA
2 varieties of salivary secretion:
1. Spontaneous : Occurs all the time, without any known
stimulus this keeps mouth moist all the time.
2. Stimulated : Occurs of known stimulus may be
1. Psychological
2. Visual
3. Taste
4. Others (during vomiting)
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97. Secretory Unit (salivon)
• The basic unit “salivon” consists of:
• Acinus -initial secretory process
• Intercalated duct -initial portion of duct
• Striated duct -modification of secretory product
• Myoepithelial cells surround acinus and intercalated duct
contraction of which moves saliva and prevents development
of back pressure
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98. Age changes
• Generalized loss of salivary gland parenchymal tissues occurs.
• Lost salivary cells often replaced by adipose tissues.
• Increase in fibrous connective tissue and vascular cells
• Gradual reduction in proportional acinar volume in major
salivary glands.
• Decreased production of saliva
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100. Saliva in dental caries
• Decreased saliva flow rate, decreased buffer capacity,
increased number of S. mutans and Lactobacilli in saliva are
usually associated with increased caries prevalence.
• Similarly, decreased level of certain salivary proteins such as
proline-rich proteins (PRP1, PRP3), histatin 1, and statherin is
associated with signifcantly higher caries-susceptibility
4/30/2015 115
101. Saliva and periodontal disorders
• Several marker proteins, saliva may be used for periodontal
disorder screening.
• The levels of proteolytic granulocyte enzyme elastase,
protease inhibitor alpha1-antitrypsin,, and elastase inhibitor
alpha2-macroglobulin may increase considerably under
gingivitis and/or periodontitis.
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102. Saliva and xerostomia
• In xerostomia usually resting unstimulated whole saliva flow
rate is less than 0.1.0.2 mL/min and stimulated flow rate is
less than 0.4.0.7 mL/min.
• In serious cases, saliva demonstrates low pH and buffer
capacity, increased total protein albumin and sodium
concentration, decreased amylase/protein ratio, and high
lactobacillus and yeast concentration.
4/30/2015 117
103. • Moreover, the level of alpha2-macroglobulin is also a good
indicator of an individual’s periodontal status).
• Salivary level of 3-hydroxy-fatty acids (lipid constituent of
lipopolysacharide endotoxin of several anaerobic bacteria) are
also good indicators of chronic periodontitis.
• Albumin may also correlate with gingival inflammation.
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104. 4/30/2015 121
The most important salivary changes in several systemic
conditions
Condition Usual but not speciÞc changes in the saliva
Anxiety Decrease of flow rate
Depression Decrease of flow rate
Acute stress Decrease of sIgA,
Increase of amylase, salivary chaperon Hsp70, stress
hormones
Prompt changes of mucins. adhesive properties
Sj¨ogren.s syndrome Decrease of flow rate, phosphate
Increase of sodium, chloride and several salivary proteins
Cystic Þbrosis Increase of electrolytes, lipids, and prostaglandin E2
Unusual form of EGF
