SALIVARY GLANDS
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Transcript of SALIVARY GLANDS
SALIVARY GLANDSSALIVARY GLANDS
Oral Histology Oral Histology Dent 205Dent 205
Summer semesterSummer semester2005/20062005/2006
Salivary GlandsSalivary Glands CharacteristicsCharacteristics
Compound – more than one tubule entering the main ductCompound – more than one tubule entering the main duct Tubuloacinar – morphology of secreting cellsTubuloacinar – morphology of secreting cells Merocrine – only secretion of the cell is releasedMerocrine – only secretion of the cell is released Exocrine – secretion onto a free surfaceExocrine – secretion onto a free surface
PhysiologyPhysiology Stimulants-taste and masticationStimulants-taste and mastication Autonomic nervous system – Afferent nervesAutonomic nervous system – Afferent nerves Salivary centreSalivary centre Autonomic nervous system – Efferent nervesAutonomic nervous system – Efferent nerves SecretionSecretion
Classification of Salivary GlandsClassification of Salivary Glands SizeSize
MajorMajor ParotidParotid SubmandibularSubmandibular SublingualSublingual
Minor: scattered throughout the oral Minor: scattered throughout the oral mucosamucosa
Labial, buccal, palatoglossal, palatal, and Labial, buccal, palatoglossal, palatal, and lingual mucosaelingual mucosae
Not present in gingivae and dorsum of Not present in gingivae and dorsum of anterior 2/3 of the tongueanterior 2/3 of the tongue
SecretionSecretion MucousMucous Serous Serous MixedMixed
SalivaSaliva
ConstituentsConstituents Water-99%Water-99% OrganicOrganic
ProteinsProteins GlycoproteinsGlycoproteins EnzymesEnzymes
InorganicInorganic MineralsMinerals
SalivaSaliva
FunctionsFunctions LubricationLubrication
MucinMucin Physical protection of oral mucosaPhysical protection of oral mucosa
TasteTaste Antibacterial and immunityAntibacterial and immunity
LysozymeLysozyme IgA – produced by plasma cellsIgA – produced by plasma cells
DigestionDigestion AmylaseAmylase
BufferingBuffering MineralsMinerals Helps in maintaining the integrity of enamelHelps in maintaining the integrity of enamel
Wound healing and upper GI mucosal integrityWound healing and upper GI mucosal integrity Epidermal Growth Factor – produced and secreted by the submandibular salivary glandsEpidermal Growth Factor – produced and secreted by the submandibular salivary glands
Blood coagulationBlood coagulation KallikreinKallikrein
Salivary GlandsSalivary Glands Main tissue elementsMain tissue elements
Glandular secretory tissueGlandular secretory tissue ParenchymaParenchyma EctodermalEctodermal Acini and duct epitheliumAcini and duct epithelium
Supporting Connective tissueSupporting Connective tissue StromaStroma MesodermalMesodermal
Macro-to-microscopic levelsMacro-to-microscopic levels GlandGland LobeLobe LobuleLobule Secretory units – AciniSecretory units – Acini
The Secretory Units The Secretory Units - ACINI- ACINI
A grape-like cluster of A grape-like cluster of parenchymal cells around a parenchymal cells around a lumenlumen
TypesTypes SerousSerous MucousMucous MixedMixed
Serous demilunes capping Serous demilunes capping mucous cellsmucous cells
Myoepithelial cells around the Myoepithelial cells around the aciniacini Contactile cells with several Contactile cells with several
processesprocesses Synonyms: basket cellsSynonyms: basket cells
The Duct SystemThe Duct System Intra-lobularIntra-lobular
Acinus lumenAcinus lumen Intercalated ductsIntercalated ducts Striated ductStriated duct* In intra-lobular system, * In intra-lobular system,
composition is affectedcomposition is affected Plasma cells in stromaPlasma cells in stroma ElectrolytesElectrolytes Epidermal GF and KallikreinEpidermal GF and Kallikrein
Inter-lobular Inter-lobular Collecting ductsCollecting ducts*The inter-lobular system is inert, *The inter-lobular system is inert,
does not affect the compositiondoes not affect the composition
StromaStroma
Connective tissueConnective tissue Mesenchymal originMesenchymal origin Macro-to-microscopic levelsMacro-to-microscopic levels
CapsularCapsular Inter-lobar Inter-lobar Inter-lobularInter-lobular Inter-acinousInter-acinous
Capsular, inter-lobar, and inter-Capsular, inter-lobar, and inter-lobular septa contain blood vessels lobular septa contain blood vessels and nervesand nerves
ConstituentsConstituents Collagen fibersCollagen fibers FibroblastsFibroblasts Fat cellsFat cells
With age, there is a decrease in With age, there is a decrease in parenchyma and an increase in parenchyma and an increase in stroma (esp. far cells)stroma (esp. far cells)
Synthesis of SalivaSynthesis of Saliva
Active secretory processActive secretory process Not a blood ultra-filtrateNot a blood ultra-filtrate Serous cellsSerous cells
Watery proteinaceous fluid contains amylaseWatery proteinaceous fluid contains amylase Mucous cellsMucous cells
Proteins linked to a greater amount of carbohyratesProteins linked to a greater amount of carbohyrates Plasma cellsPlasma cells
IgAIgA
Secretion of SalivaSecretion of Saliva Throughout the dayThroughout the day
Low level in generalLow level in general Periodic large addition from major glandsPeriodic large addition from major glands
Average flow rate (90% from Major SG)Average flow rate (90% from Major SG) 0.3 ml/min0.3 ml/min 500-700 ml/day500-700 ml/day
Contribution of gingival fluidsContribution of gingival fluids SecretionSecretion
SpontaneousSpontaneous Small amounts from sublingual and minor SGsSmall amounts from sublingual and minor SGs
Stimulated (nerve-mediated)Stimulated (nerve-mediated) The bulk of saliva from all glandsThe bulk of saliva from all glands Parotid and Submandibular SGs do not secret spontaneouslyParotid and Submandibular SGs do not secret spontaneously
Anaesthesia ceases secretion as it is nerve-mediatedAnaesthesia ceases secretion as it is nerve-mediated
Serous cellsSerous cells
Light MicroscopyLight Microscopy Basophilic because of Rough Basophilic because of Rough
Endoplasmic ReticulumEndoplasmic Reticulum Characteristic granular appearance Characteristic granular appearance
with H & Ewith H & E Round prominent nuclei located at the Round prominent nuclei located at the
basal third of the cellbasal third of the cell Ultra-structureUltra-structure
Wedge-shaped outlineWedge-shaped outline Basal lamina separates from stromaBasal lamina separates from stroma Luminal part contains zymogen Luminal part contains zymogen
granulesgranules MicrovilliMicrovilli Desmosomes, gap and tight junctionsDesmosomes, gap and tight junctions
Mucous cellsMucous cells
Appear pale in H & E stainsAppear pale in H & E stains Basally-compressed nucleiBasally-compressed nuclei Acini may be surrounded Acini may be surrounded
by crescent-shaped serous by crescent-shaped serous demilunesdemilunes
Debate whether demilunes Debate whether demilunes are connected with the are connected with the lumenlumen
Mucin granulesMucin granules
Acinus lumen
Serous demilunes
Mucous cells
Myoepithelial cellsMyoepithelial cells
Lie between basal lamina and basal Lie between basal lamina and basal membranes of acinar cells and ICDmembranes of acinar cells and ICD
Around acinar cellsAround acinar cells DendriticDendritic Long tapering processesLong tapering processes
Around ICDAround ICD LongitudinalLongitudinal Few short processesFew short processes
ContracttionContracttion ParasympatheticParasympathetic SympatheticSympathetic
Ultra-structureUltra-structure Flattened nucleusFlattened nucleus Desmosomes with parenchymal cellsDesmosomes with parenchymal cells Gap junctions and hemidesmosomes with Gap junctions and hemidesmosomes with
basal laminabasal lamina
Intercalated ductsIntercalated ducts
Drainage from several aciniDrainage from several acini Compressed between the aciniCompressed between the acini Cuboidal epithelial cellsCuboidal epithelial cells Prominent nucleiProminent nuclei In Parotid, they are long, In Parotid, they are long,
narrow, and branchingnarrow, and branching
Striated ductsStriated ducts
Larger and longer than ICDLarger and longer than ICD Simple columnar epitheliumSimple columnar epithelium Cells have large centrally-located nucleiCells have large centrally-located nuclei Luminal surfaces have microvilliLuminal surfaces have microvilli Basal surfaces separated from Basal surfaces separated from
connective tissue by basal laminaconnective tissue by basal lamina Striation (in light microscopy) Striation (in light microscopy)
corresponds to multiple infoldings of corresponds to multiple infoldings of the basal membrane of the cellsthe basal membrane of the cells
DesmosomesDesmosomes Electrolyte re-absorption (active) and Electrolyte re-absorption (active) and
secretionsecretion Secretion of Epidermal GF and Secretion of Epidermal GF and
KallikreinKallikrein
Collecting ductsCollecting ducts Bi-layered epithelium (lacks Bi-layered epithelium (lacks
striation)striation) Columnar epithelial layerColumnar epithelial layer Basal layerBasal layer
As it enlarges, it gets a As it enlarges, it gets a connective tissue adventitiaconnective tissue adventitia
Terminated as stratified Terminated as stratified epithelium to merge with the epithelium to merge with the oral mucosaoral mucosa
Parotid glandParotid gland
The largestThe largest Serous AciniSerous Acini Adult PG vs. Infant’s PGAdult PG vs. Infant’s PG Fat cells vs. ageFat cells vs. age
Submandibular Submandibular glandgland
22ndnd largest largest Mixed serous-Mixed serous-
mucous secretion mucous secretion (7:3)(7:3)
Intercalated ducts Intercalated ducts are short and are short and difficult to locatedifficult to locate
Striated ducts are Striated ducts are long and obvious long and obvious
Sublingual glandsSublingual glands 2 segments all empty 2 segments all empty
to the sublingual foldto the sublingual fold Major sublingual glandMajor sublingual gland 8 - 30 mixed minor SGs8 - 30 mixed minor SGs
Mixed gland, mucous Mixed gland, mucous outnumber serous cellsoutnumber serous cells
Most of the serous Most of the serous cells are in demilunescells are in demilunes
Lacking striated ductsLacking striated ducts
Minor Salivary glandsMinor Salivary glands
Primarily mucousPrimarily mucous Labial, buccal, palatal, palatoglossal, and Labial, buccal, palatal, palatoglossal, and
linguallingual Lingual glandsLingual glands
Anterior glandsAnterior glands Embedded in muscle near the ventral surface of the Embedded in muscle near the ventral surface of the
tonguetongue Mucous glandsMucous glands
Posterior glandsPosterior glands At the root of the tongueAt the root of the tongue Mucous glandsMucous glands
Von Ebner glandsVon Ebner glands SerousSerous Associated with the Circumvallate papillaeAssociated with the Circumvallate papillae
Clinical ConsiderationsClinical Considerations Dry Mouth (xerostomia)Dry Mouth (xerostomia)
CausesCauses Ageing – Parenchymal tissue < StromaAgeing – Parenchymal tissue < Stroma DrugsDrugs
Central action on the salivary centreCentral action on the salivary centre Diuretics, sedatives, hypnotics, antihistamines, antihypertensives, Diuretics, sedatives, hypnotics, antihistamines, antihypertensives,
antipsychotics, antidepressants, anticholinergics, and appetite suppressantsantipsychotics, antidepressants, anticholinergics, and appetite suppressants Loss / destruction of salivary tissueLoss / destruction of salivary tissue
RadiotherapyRadiotherapy Autoimmune disordersAutoimmune disorders
Sjogren’s syndrome – destruction by lymphoid tissue (autoimmune disease)Sjogren’s syndrome – destruction by lymphoid tissue (autoimmune disease) Salivary gland surgerySalivary gland surgery
Endocrine disordersEndocrine disorders DiabetesDiabetes HyperthyroidismHyperthyroidism
Clinical Considerations Clinical Considerations
Dry mouth (xerostomia)Dry mouth (xerostomia) Signs and symptomsSigns and symptoms
Dry, red, glossy atrophic mucosaDry, red, glossy atrophic mucosa Difficulty chewing, swallowing, or speakingDifficulty chewing, swallowing, or speaking Altered / diminished taste abilityAltered / diminished taste ability Dental cariesDental caries
Saliva contains re-mineralising mineralsSaliva contains re-mineralising minerals Periodontal diseasePeriodontal disease Candidal infectionCandidal infection
TreatmentTreatment Consider stopping offending medication Consider stopping offending medication Commercial saliva substituteCommercial saliva substitute Fluoride SupplementationFluoride Supplementation Scrupulous dental careScrupulous dental care
Clinical considerationsClinical considerations Obstructive disordersObstructive disorders
Sialolithiasis (salivary calculi)Sialolithiasis (salivary calculi) 80% in submandibular SG80% in submandibular SG
Mucoceles and cystsMucoceles and cysts Minor SGsMinor SGs Retention of mucous outside the ductRetention of mucous outside the duct
RanulaRanula Submandibular and sublingual SGsSubmandibular and sublingual SGs
Inflammatory disorders (Sialadenitis)Inflammatory disorders (Sialadenitis) Viral Viral
MumpsMumps Bacterial – uncommonBacterial – uncommon
Suppurative parotitisSuppurative parotitis Autoimmune diseasesAutoimmune diseases
Sjogren’s syndromeSjogren’s syndrome Salivary gland tumoursSalivary gland tumours
http://www.fo.usp.br/estomato/patobucal/images/mucocele.jpg
http://www.infocompu.com/adolfo_arthur/images/ranula.jpg