2. Terminologies
• Glands are basically divided into
• Endocrine glands — are glands that secrete their products
through the basal lamina and lack a duct system.
• Exocrine glands — secrete their products through a duct
the glands in this group can be divided into three groups:
3. • Merocrine glands — cells secrete their substances
by exocytosis (e.g., mucous and serous glands). Also called
"eccrine".
• Apocrine glands — a portion of the secreting cell’s body is
lost during secretion.
• Holocrine glands — the entire cell disintegrates to secrete
its substances (e.g., sebaceous glands)
4. • The type of secretory product of an Exocrine gland may
also be one of three categories:
• Serous glands — secrete a watery, often protein-rich
product.
• Mucous glands — secrete a viscous product, rich
in carbohydrates (e.g., glycoproteins).
• Sebaceous glands — secrete a lipid product. These glands
are also known as oil glands.
5. Introduction
• Definition: Salivary glands are compound, tubuloacinar,
merocrine, exocrine glands the ducts of which open into
oral cavity.
• The oral cavity is kept moist by a film of fluid called saliva
that coats the teeth and mucosa.
• Saliva is a complex fluid produced by the salivary glands.
6. CLASSIFICATION OF SALIVARY GLANDS
• Based on the size & location, they
are classified as:
– Major salivary glands
– Minor salivary glands
• Major salivary glands - three pairs
– Parotid gland
– Submandibular gland
– Sublingual gland
• Located outside the oral cavity
• Secretion reach the mouth through
ductal system
7. Introduction
• Minor salivary located in various parts of the oral cavity
– Labial
– Lingual
– Palatal
– Buccal
– Glossopalatine
– Retromolar
• Present in the submucosal layer
• Opens onto the mucosal surface by short ductal openings
8. • Based on the type of secretions
• Serous secreting Glands
• e.g. parotid glands, von Ebner’s gland.
• Mucus secreting glands
• e.g. glands of blandin & nuhn, glosso palatine glands.
• Mixed glands
• e.g submandibular gland, sub lingual gland
9. Anatomy
• PAROTID GLAND (para=around, otic=ear)
• Largest major salivary gland
• It is purely serous gland.
• It weighs about 15 gms.
• Superficial portion of the gland lies in front of the external
ear and its deeper part filling the retromolar fossa.
10. • Arteries: External carotid artery,
maxillary artery, superficial
temporal, posterior auricular
artery
• Veins: retromandibular vein is
formed within the gland by
union of superficial temporal
and maxillary vein.
• Nerves : facial nerve enters the
gland and divides in to terminal
branches within the gland.
11. • PAROTID DUCT:
• The main excretory duct the stensons duct crosses the
masseter and pierces the buccinator to open at papilla at
buccal mucosa opposite to maxillary second molar.
• The duct measures 4-6 mm in length and 5 mm in
diameter.
• A small portion of parotid accompanies duct forming
accessory gland.
12. • BLOOD SUPPLY:
• Blood supply is by external carotid artery and veins drain
in to external jugular vein.
• LYMPHATIC DRAINAGE:
• Lymph drains in to parotid nodes and from there to upper
deep cervical lymph nodes.
13. • 1.parasympathetic fibers:
• These are secretomotor
• preganglionic fibers - inferior
salivatory nucleus 9 th nerve
rely otic ganglion
• postganglionic fibers
auriculotemporal nerve
gland
• 2.sympathetic nerves are
vasomotor and are derived from
plexus around external carotid
artery.
• 3.sensory nerves come from
auriculotemporal nerve.
Nerve supply
15. SUBMANDIBULARGLAND
• Second largest salivary gland. also called submaxillary
salivary gland.
• It is mixed type of gland with both serous and mucous units
but serous units predominate.
• Superficial part: this part of gland fills diagastric triangle.
• Deep part: It is deep to mylohyoid and superficial to
hyoglossus and styloglossus.
16. • Submandibular duct:
• The main excretory duct is whartons duct, runs forward
above the mylohyoid muscle lying just below mucosa and
floor of mouth .
• It opens on sublingual papillae also called caruncula
sublingualis, lateral to lingual frenum.
17. • Blood supply:
• It is supplied by facial artery. Veins drain in to common
facial or lingual vein.
• Lymphatic drainage:
• Deep cervical and jugular group of nodes.
18. Nerve supply
• The secretomotor pathway begins near superior salivatory
nucleus. Preganglionic fibers pass through the sensory root of
facial nerve, the geniculate ganglion, the chordatympani and
the lingual nerve to reach submandibular ganglion.
Postganglionic fibers emerge from the ganglion and enter
submandibular gland.
20. SUBLINGUAL GLAND
• It is smallest of the major salivary glands.
• The sublingual gland lies between floor of the mouth,
below mucosa and above mylohyoid muscle.
• It is a mixed gland, but mucous units predominate.
21. • Sublingual duct
• It opens near submandibular duct.
• Several small ducts, ducts of Rivinus open independently
along sublingual fold.
24. DEVELOPMENT ANDGROWTH
• Salivary glands arise from the ectoderm of the oral cavity.
• During embryonic life salivary gland is formed at specific
location of the oral cavity through the growth of bud of oral
epithelium in to underlying mesenchyme.
• Parotid & submandibular glands appear during 6th week of
intrauterine life.
• Sublingual gland during 7-8th week of I.U life.
• Minor salivary glands begin their development during 3 rd
month of I u life
25. • 3 stages are seen in the development of salivary glands:
• 1st stage: shows the development of anlage and the
development of gland with dichromatic branched ducts.
• 2nd stage: shows further differentiation of gland and early
formation of lobules and canalization of ducts. 7th month of
intrauterine life
• 3rd stage: begins at 8th embryonal month and leads to
further maturation of glands with acinar and intercalated
duct differentiation.
26. • Experimental studies has shown that branching
morphogenesis requires interaction between epithelium
and mesenchyme.
• Signaling molecules including fibroblast growth factor
family, sonic hedgehog, TGF beta, play a major role in
development of branches.
27. Structure
• Salivary glands consists of
– Series of branched ducts
– Terminating in spherical or
tubular secretory end pieces or
acini
• Analogy – bunch of grapes
• Stems – ducts
• Grapes – secretyory end pieces
• Main excretory duct – empties into
oral cavity
28. • Each gland is divided into lobes and
lobules by means of connective tissue septa
Intercalated ducts (smallest) (intralobular)
Striated ducts (intralobular)
Excretory ducts (interlobular)
30. • The basic functional unit of salivary gland is terminal
secretory unit called –acini
• The secretory unit is made of serous, mucous cells and
myoepithelial cells.
• The cells in the acini rest on a basement membrane the
junctional complexes hold the cells together and the
myoepithelial cells are located on the surface of acini.
• The central lumen is star shaped because of extension of
lumen between the cells – intercellular canaliculi.
• Mucous acini has larger lumen than serous acini.
• The central lumen continue via fine series of ducts which
finally form the excretory duct – ductal system
31.
32. SEROUS CELLS
• Morphology: Pyramidal with broad base on the basement
membrane and apex towards lumen.
• Spherical nucleus placed at basal region.
• Basal cytoplasm is packed with parallelly stacked, RER
which is placed basal and lateral to cell nucleus.
• The lumen usually has finger like extensions located between
adjacent cells called intercellular canaliculi that increase the
size of luminal surface of the cells.
33.
34. • Secretory granules: ZYMOGEN granules - glycolated
proteins stored in a vacuole
• Apical cytoplasm shows secretory granules -1 mm in dia.
• The granules are closely apposed but retain their
individuality.
• Visualized in sections stained with toludine blue or special
stains
• Immature granules - paler in density, mature granules -
electron dense.
• Numerous granules in luminal portion of resting cell
35. • Intercellular junctions between serous cells:
• The tight junctions
• The adhering junctions and desmosomes - hold the
adjacent cells together and also help in cell signaling.
• Gap junctions allow the passage of ions and small
molecules between the cells.
36.
37. • Its structure differs from serous cells, the apex of the cells
appear empty except for thin strands of cytoplasm forming a
trabecular network.
• Nucleus and the rims of cytoplasm are compressed against
the base of the cell.
• Nucleus of the mucous cell is oval or flattened in shape &
located just above the basal plasma membrane.
• Mucous cells show accumulation of large amount of
secretory product in apical cytoplasm
Mucous cells
38.
39. • Mucous cell is seen to be filled with pale, translucent
secretary droplets containing scattered flocculent material.
• Unstained in routine histologic sections. Special stains like
PAS and alcian blue it is heavily stained.
• EM studies :the secretory granules appear swollen, their
membranes are disrupted and fuse with one another.
• Like serous cells mucous cells are joined by many cell to
cell junctions.
40. • Mucous secretion differs from serous secretion in two
ways:
• 1.they have little or no enzymatic activity and mainly
serves for lubrication and protection of oral tissues.
• 2.the ratio of carbohydrate to protein is greater and large
amount of sialic acid and occasionally sulfated sugars is
present.
41.
42.
43. MYOEPITHELIALCELLS
• Contractile cells associated with secretory end pieces and
intercalated ducts of salivary glands
• Myoepithelial cells are similar to smooth muscle cells but
are derived from the epithelium
• These cells are locate between the basal lamina and
secretory or ductal cells
• The plasma membrane of the myoepithelial cells joins the
basal membrane of parenchymal cells by desmosomes.
44. • These are stellate or spider like cells with flattend nucleus
and flat perinuclear cytoplasm and long branching process
that embrace secretory and duct cells.
• Their appearance is like basket cradling the secertory unit
so called as basket cells.
• The cell organelles are restricted to perinuclear cytoplasm.
45. • 1.their structure is similar to smooth muscles.
• 2.immunoflourescence studies indicate presence of myosin,
actin
• 3.There is regular pulsatile movement of entire unit.
• Difficult to identify under light microscope
• Can be identified by immunohistochemical or
immunofluorescent techniques.
• Contain cytokeratin intermediate filament and contractile
actin filaments.
• This helps to identify them immunohistochemically.
46. • Functions:
• Accelerate the initial outflow of saliva from acini.
• Contribute to secretary pressure in the acini or duct.
• Support the underlying parenchyma and reduce the back
permeation of the fluid
• Recent studies show that ME cells are involved in signaling
the secretory cells and protecting the salivary gland tissue.
• The ME cells also produce a number of proteins that has
tumor suppressor activity, such as protienase inhibitors
and angiogenic factors which act as barriers against
invasive epithelial neoplasms.
48. Intercalatedducts
• Lined by single layer of cuboidal cells with a relatively clear
appearing cytoplasm
• In Electron Microscopic studies the intercalated duct cells
resemble serous cells.
49. • Functions:
• They modify saliva through secretory and resorptive
processes. They contribute to substances like lactoferrin etc.
• Intercalated ducts also houses undifferentiated cells which
can undergo differentiation and replace damage cells in the
end pieces or striated ducts.
50. Striatedducts
• Lined by tall columnar epithelial cells with centrally placed
nuclei.
• The cytoplasm is eosinophilic and show prominent striations
at the basal end of the cells, perpendicular to basal surface.
• EMstudies: basal cytoplasm of the striated duct cells show
deep infoldings of the plasma membrane and many large
mitochondria usually radially oriented are located between
the infoldings indicating that the cell is involved in active
transport.
51.
52. • Functions:
• These are site of absorption of sodium, chloride and
excretion of pottasium and bicarbonate. The reabsorption
is against concentration gradient so needs more energy
53. Excretory ducts
• As the excretory duct enlarges it contains two layers
:mucosa and connective tissue adventitia.
• The mucosal epithelium is of pseudostratified columnar
epithelium ocassionally goblet and ciliated cells are seen.
• The ductal epithelium slowly undergoes transformation to
cuboidal and finally to stratified squamous epithelium
54. Ductal modification of saliva
• Occurs through reabsorption and secretion of electrolytes.
• Abundant transporters that produces net reabsorption of
Na+ and Cl- ions resulting in formation of hypotonic
saliva. the ducts also secrete k+ and HCO3
• At high flow rates the saliva has higher concentration of
Na and cl and lower conc of pottasium
55. Connective tissue elements
• The cells include fibroblasts, macrophages, mast cells
occasional leucocytes, fat cells and plasma cells. The cells
along with the fibres are embeded in ground substance
composed of proteoglycans and glycoproteins.
• The connective tissue forms the capsule for the gland and
divides the gland in to lobules.
• The vascular supply of the gland is also embeded within
the connective tissue.
56. Minor salivary glands
• These are located beneath the epithelium in almost all parts
of oral cavity. they open by short ducts directly in to mouth.
they lack distinct capsule and instead mixing with the
connective tissue mucosa.(salivary glands are absent in
anterolateral part of hard palate and Gingiva)
57. LABIAL ANDBUCCAL GLANDS
The glands of the lips and cheeks are called labial and
buccal glands.
Mixed glands consisting of mucous acini with serous
demilunes.
Intercalated ducts are variable in length, and intralobular
ducts posses only a few cells with basal striations.
58. GLOSSOPALATINE GLANDS
• These are pure mucous glands,
• They are principally localized to the region of isthmus in
the glossopalatine fold but may extend from posterior
extension of sublingual gland to glands of soft palate.
59. PALATINE GLANDS
Pure mucous glands.
Several hundreds of glandular aggregates in the lamina
propria in the posterolateral regions of the hard palate,
and in the submucosa of the soft palate and the uvula.
The excretory ducts have irregular contour and their
openings on the palatal mucosa are large and easily
recognizable.
60.
61. LINGUAL GLANDS
Anterior lingual glands: glands of Blandin and Nuhn:
Located near the apex of the tongue.
Chiefly mucous in nature, where as posterior portions are
mixed.
The ducts open near ventral surface of tongue near lingual
frenum.
Posterior lingual mucous glands:
These are located posterior and lateral to vallate papillae
and in association with lingual tonsil.
Mucous in character.
Their ducts open on the dorsal surface of tongue.
62.
63. Posterior lingual serous glands: VonEbners glands
• These are located between muscle fibers of the tongue
below the vallate papillae.
• These are purely serous glands.
• Their ducts open at trough of vallate papillae
• Functions:
• Their secretions are belived to wash out the trough of the
papillae.
• Histochemical studies has localized antibacterial enzymes
peroxidase and lysozyme.
• Biochemical studies demonstrated enzyme with lipolytic
activity lingual lipase.
64. Saliva
• Saliva is the secretions of major and minor salivary glands
along with desquamated epithelial cells, microorganisms,
food debris, serum components and inflammatory cells.
• Each gland secretions differs in amount and content
• Parotid gland – watery saliva, enzymes (amylase), proline
rich proteins, glycoproteins
• Submandibular gland – in addition to the above
glycosalated substances (mucins)
• Sublingual gland – viscous saliva rich in mucins
