4. Major glands
• Parotid: so-called watery serous saliva rich
in amylase, proline-rich proteins
– Stenson’s duct
• Submandibular gland: more mucinous
– Wharton’s duct
• Sublingual: viscous saliva
– ducts of Rivinus; duct of Bartholin
5.
6. Minor glands
• Minor salivary glands are not found within
gingiva and anterior part of the hard palate
• Serous minor glands=von Ebner below the sulci of
the circumvallate and folliate papillae of the
tongue
• Glands of Blandin-Nuhn: ventral tongue
• Palatine, glossopalatine glands are pure mucus
• Weber glands
7. Functions
• 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
8. Functions
• Buffering (phosphate ions and bicarbonate)
– bacteria require specific pH conditions
– plaque microorganisms produce acids from
sugars
10. Functions
• Antimicrobial
– lysozyme hydrolyzes cell walls of some
bacteria
– lactoferrin binds free iron and deprives bacteria
of this essential element
– IgA agglutinates microorganisms
11. Functions
• Maintenance of tooth integrity
– calcium and phosphate ions
• ionic exchange with tooth surface
12. Functions
• Tissue repair
– bleeding time of oral tissues shorter than other
tissues
– resulting clot less solid than normal
– remineralization
14. Embryonic development
• The parotid: ectoderm (4-6 weeks of embryonic
life)
• The sublingual-submandibular glands: endoderm
• The submandibular gland around the 6th week
• The sublingual and the minor glands develop
around the 8-12 week
• Differentiation of the ectomesenchyme
• Development of fibrous capsule
• Formation of septa that divide the gland into lobes
and lobules
15.
16.
17.
18.
19. Serous cells
• Seromucus cells=secrete also polysaccharides
• They have all the features of a cell specialized for
the synthesis, storage, and secretion of protein
– Rough endoplasmic reticulum (ribosomal sites--
>cisternae)
– Prominent Golgi-->carbohydrate moieties are added
Secretory granules-->exocytosis
20. Serous cells
• The secretory process is continuous but cyclic
• There are complex foldings of cytoplasmic
membrane
• The junctional complex consists of:
– Tight junctions (zonula occludens)-->fusion of outer
cell layer
– Intermediate junction (zonula adherens)-->intercellular
communication
– Desmosomes-->firm adhesion
31. Formation and Secretion of Saliva
• Primary saliva
– Serous and mucous cells
– Intercalated ducts
• Modified saliva
– Striated and terminal ducts
– End product is hypotonic
33. Fluid and Electrolytes
• Parasympathetic innervation
• Binding of acetylcholine to muscarinic
receptors
– Activation of phospholipase IP3 release of
Ca2+
opening of channels K+
, Cl-
Na+ in
– K+
and Cl-
in
– Also another electrolyte transport mechanism
through HCO3-
• Noepinephrine via alpha-adrenergic receptors
– Substance P activates the Ca2+
34. Myoepithelial cells
• One, two or even three myoepithelial cells
in each salivary and piece body
• Four to eight processes
• Desmosomes between myoepithelial cells
and secretory cells
• Myofilaments frequently aggregated to
form dark bodies along the course of the
process
35. Myoepithelial cells
• The myoepithelial cells of the intercalated ducts
are more spindled-shaped and fewer processes
• Ultrastructurally very similar to that of smooth
muscle cells
• Functions of myoepithelial cells
– Support secretory cells
– Contract and widen the diameter of the intercalated
ducts
– Contraction may aid in the rupture of acinar cells of
epithelial origin
36.
37.
38.
39.
40.
41. Intercalated Ducts
• Small diameter
• Lined by small cuboidal cells
• Nucleus located in the center
• Well-developed RER, Golgi apparatus,
occasionally secretory granules, few microvilli
• Myoepithelial cells are also present
• Intercalated ducts are prominent in salivary glands
having a watery secretion (parotid).
42.
43. Striated Ducts
• Columnar cells
• Centrally located nucleus
• Eosinophilic cytoplasm
• Prominenty striations
– Indentations of the cytoplasmic membrane with many
mitochondria present between the folds
• Some RER and some Golgi, short microvilli
• Modify the secretion
– Hypotonic solution=low sodium and chloride and
high potassium
• Basal cells
44.
45.
46.
47.
48. Terminal excretory ducts
• Near the striated ducts they have the same
histology as the striated ducts
• As the duct reaches the oral mucosa the
lining becomes stratified
• Goblet cells, basal cells, clear cells.
• Alter the electrolyte concentration and add
mucoid substance.
49.
50. Ductal modification
• Autonomic nervous system
• Striated and terminal ducts
• Modofication via reabsorption and secretion of
electrolytes
• Final product is hypotonic
• Rate of salivary flow
– High: Sodium and chlorine up; potassium down
53. Nerve supply
• No direct inhibitory innervation
• Parasympathetic and sympathetic impulses
• Parasympathetic are more prevalent.
• Parasympathetic impulses may occur in
isolation, evoke most of the fluid to be
excreted, cause exocytosis, induce
contraction of myoepithelial cells
(sympathetic too) and cause vasodilatation.
54. Nerve supply
• There are two types of innervation:
Epilemmal and hypolemmal
• beta-adrenergic receptors that induce
protein secretion
• L-adrenergic and cholinergic receptors that
induce water and electrolyte secretion
55. Hormones can influence the function of the
salivary glands. They modify the salivary
content but cannot iniate salivary flow.
56. Age changes
• Fibrosis and fatty degenerative changes
• Presence of oncocytes (eosinophilic cells
containing many mitochondria)
57. Clinical Considerations
• Obstruction
• Role of drugs
• Systemic disorders
• Bacterial or viral infections
• Therapeutic radiation
• Formation of plaque and calculus
