Embed Size (px)
Citation preview
ORAL MUCOSAOral HistologyOral Histology
Dent 206Dent 206
Functions of oral Mucosa Mechanical protection Barrier against microorganisms & toxins Immunological defense Lubrication Innervation
Touch Proprioception Taste Pain
Structure of Mucosa
Epithelium (vs. epidermis of skin) Stratified squamous Ectodermal or endodermal origin
Basal lamina Lamina Propria (vs. dermis of skin)
Papillary Layer Reticular layer
Submucosa (vs. subcutaneous tissue) Loose connective tissue Contains
Glandular tissue Adipose tissue Large blood vessels and nerves
Types of Oral Mucosa
Masticatory muscosa Lining mucosa Specialized mucosa
Masticatory Mucosa Where there is compression & friction Rough, thicker and whiter in colour compared to
lining mucosa Keratinized or parakeratinized epithelium Thick lamina propria bound down directly &
tightly to underlying bone Covering
Hard palate Oral surface of gingiva
Lining Mucosa Not subject to high level of friction Soft, mobile and distensible Thinner & redder in colour compared to
masticatory mucosa Non-keratinized epithelium Loose lamina propria Covering
Oral surface of cheeks, lips, alveolus, dentogingival region, floor of the mouth, ventral surface of tongue and soft palate
Specialized mucosa
Keratinized epitheliumCovers
Dorsum of the tongueAssociated with taste sensationGustatory mucosa
Vermilion zone of the lip
Epithelium Layers
Stratum germinativum (stratum basale)
Stratum spinosum (prickle cell layer)
Stratum granulosum (granular layer) Stratum corneum (Keratinized or
cornified layer) Progressive maturation /
differentiation process Superficial cells are shed & replaced
from below Turnover is fastest in junctional &
sulcular epithelia (5 days) Followed by lining mucosa Masticatory mucosa has the slowest
turnover rate
Stratum germinativum Single cuboidal cell layer Adjacent to lamina propria The only layer where
mitosis occurs Are all stem cells? Least differentiated cells Non-keratinocytes
Stratum spinosum Several cells thick Round or ovoid cells Larger & more mature than
those of s. germinativum Contain
Tonofilaments & involucrin Phospholipid granules (Odland
bodies) in upper part of stratum spinosum
Increased desmosomes (shrinkage during preparation gives the spiny appearance)
Stratum granulosum Cells of further increase in maturation Cells larger & flatter Contain
Tonofilaments & tonofibrils that occupy the cytoplasm
Keratohyaline granules (contain profilaggrin)
Stratum Corneum In keratinized epithelium
Highly mature epithelial cells (squames) All cellular organelles and nucleus lost (orthokeratinzation) In gingiva, nuclei may be retained (parakeratinization) Cells are packed with Keratin Kertain consists of
Tonofilaments surrounded by Filaggrin (matrix protein)
Desmosomes are weakened to allow for shedding (desquamation)
Involucrin is cross-linked to form a cornified envelop beneath plasma membrane
Stratum Corneum In non-keratinized epithelium
No keratin Tonofilaments are less & under-
developed Lack keratohyaline granules This layer is less distinct The outer layers of non-kertinized
epithelium may be termed stratum superficiale
The layers below may be termed stratum intermedium
Keratinization
Regional distribution Adaptation to abrasion by food - rough
surface Whiter than nonkeratinized mucosa Ortho- vs. parakeratinization
Non-keratinocytes 10% of oral epithelial cells Lack tonofilaments & desmosomes (except
Merkel cells) Appears as clear cells in routine H&E staining
as they lack the cytokeratin of keratinocytes Include
Melanocytes Langerhans cells Merkel cells
Melanocytes Located in stratum germinativum Pigment (melanin)-producing cells Derived from neural crest cells Long processes that extend through upper layers Packed with granules (melanosomes) Racial variance is due to
Melanocyte size difference Number of dendritic processes Melanosomes: granule number or size Melanin: degree of dipersion and rate of degradation
Langerhans cells Dendritic cells Located in the layers above stratum
germinativum Derived from bone marrow precursors Antigen-presenting cells Involved in contact-hypersensitivity reactions,
antitumour immunity & graft rejection Contain Birbeck granules
Merkel cells Located in stratum germinativum of
masticatory epithelium Absent in lining epithelium Closed apposed to nerve fibers Thought to act as receptors Derived from neural crest cells Associated with desmosomes
Lining mucosa Location
Mucosal surface of the Lip Soft Palate Cheeks Ventral surface of the tongue Floor of the mouth Alveolar Mucosa Frena Vestibular Fornix
Lining epithelium
http://www.usc.edu/hsc/dental/ohisto/Cards/muc/09_big.html
Lip Oral surface Vermilion zone Skin surface
Oral surface
Epitheliumnonkeratinized
Lamina PropriaSeromucous minor salivary glands
SubmucosaOrbicularis Oris
Oral surface of the lip
http://www.usc.edu/hsc/dental/ohisto/Cards/muc/15_big.html
Vermilion zone Junction between skin & oral mucosa Specialized keratinized mucosa different from both skin &
oral mucosa Lacks hair follicles or glandular tissue Sebaceous glands may be present at angles of the mouth Red in colour (human characteristics)
Thin epithelium Transparent Eleidin Rich blood vessels near the surface (long papillae)
Intermediate zone Junctional region with oral surface Parakeratinized
Vermilion zone
http://www.usc.edu/hsc/dental/ohisto/Cards/muc/18_tns.html
Skin surface Skin appendages
Hair follicles Sebaceous glands Erector pili muscles Sweat glands
Subcutaneous layer Orbicularis Oris
Skin surface of the lip
Fordyce’s spots Ectopic sebaceous glands Not associated with a hair follicle Location
Corners of the mouth Buccal mucosa Soft palate
Fordyce’s spots
http://www.usc.edu/hsc/dental/PTHL501/QL/d_ql_11.html
Fordyce’s spots
http://www.usc.edu/hsc/dental/PTHL501/QL/d_ql_14.html
Soft palate Epithelium
Pink surface Lamina Propria
Highly vascularized Submucosa
Muscles Mucous minor salivary glands
Cheeks Epithelium Lamina Propria Submucosa
Fat cells Seromucous minor salivary glands Buccinator muscle
Ventral surface of the tongue Epithelium Lamina Propria Submucosa
Connective tissue and muscle fibers mixed together
*Firmly attached membrane
Ventral surface of the tongue
Floor of the mouth
Epithelium lamina Propria Submucosa
Minor salivary glands Sublingual major salivary glands
*Loosely attached membrane
Alveolar mucosa Epithelium
Nonkeratinized Lamina Propria
Dermal papillae are short and thick Numerous elastic fibers
Submucosa Loose and may contain seromucous glands
Periosteum /bone
Vestibular fornix and frena Fornix
Loosely attached to muscle Frena
Labial/buccal Folds of mucous membrane Contain connective tissues No muscles
Masticatory Mucosa Location
Gingiva Hard palate
Masticatory epithelium
Attachments Cell-to-cell
Desmosomes Epithelium to
Lamina Propria Basal Lamina
Hemidesmosomes Anchoring Fibrils
Gingiva Development
Coalescence of reduced enamel epithelium & oral epithelium
Three zones Free (marginal) gingiva Attached gingiva Interdental gingiva
Junctions Free gingival groove mucogingival junction
http://home.teleport.com/~bobh/gingiva.htm
Free gingiva
Free gingiva Surface
Smooth Keratinized Sulcular surface is not keratinized
Separated by: Gingival sulcus from the tooth Free gingival groove from the attached
gingiva
Free gingiva
http://www.usc.edu/hsc/dental/ohisto/Cards/muc/18_tns.html
Free gingiva
http://www.usc.edu/hsc/dental/ohisto/Cards/muc/18_tns.html
Free gingival - oral Surface
http://www.usc.edu/hsc/dental/ohisto/Cards/muc/18_tns.html
Attached gingiva Surface
Stippled Separated by:
Free gingival groove from the free gingiva
Mucogingival junction from alveolar mucosa
No submucosa Periosteum/ bone
Junctional epithelium
Functions Floor of gingival sulcus Attachment Protection
Different cells Fewer desmosomes High rate of turnover High metabolic activity Stratum Germinativum
cells: hemidesmosomes
Junctional epithelium
http://www.usc.edu/hsc/dental/ohisto/Cards/muc/18_tns.html
Interdental papilla and col Interdental papilla
Facial or lingual parts of gingiva between teeth Col
Epithelium of the interproximal gingival tissue connecting facial and lingual interdental papillae
Thin Nonkeratinized Concave in shape
Hard palate Epithelium
Keratinized Lamina Propria
Dense under rugue Submucosa
Fatty cells in anterior lateral area Mucous glands in the posterior lateral area Absent in the midline under median raphe
Periosteum
http://www1.us.elsevierhealth.com/SIMON/Bird/modern/EIC/graphics/7627_17_14.jpg
Rugae Epithelial folds
Function Mastication Phonation
Traction Bands Bundles of collagen
fibers in LP origin: bony palate Insertion: papillary
fibers of LP Function: anchorage
www.forsyth.org/oralpathology/ case_008b.htm
Palatal mucosa
Specialized gustatory mucosa
Location Dorsum of the tongue
4 types of papillae Filiform
Fungiform Circumvallate Foliate
Filiform and fungiform papillae
www.forsyth.org/oralpathology/ case_086b.htm
Filiform papillae Anterior 2/3s of the dorsum of
the tongue Central cores of lamina propria
covered by Ortho or parakeratinized epithelium
No taste buds Fungiform papillae
Mushroom-shaped Vascular core of lamina propria
covered by keratinized or non-keratinized epithelium
Taste buds may be found on the surface
Filiform & fungiform papillae
Circumvallate papillae
www.forsyth.org/oralpathology/ case_011.htm
Located in the posterior region of anterior 2/3 just in front of sulcus terminalis
Large & rounded Surrounded by a trench-like feature Do not project over the surface Covered by non-keratinized epithelium Taste buds found on the internal wall of
the trench Associated with Von Ebner glands
Serous minor salivary glands Empty at the floor of the trench
Von Ebner’s Glands (serous glands)
Foliate papillae
http://www.forsyth.org/oralpathology/case_010.htm
At the side of posterior 1/3 of the tongue One or two longitudinal clefts Tastes buds found within the non-keratinized
parts
Foliate papillae
http://education.vetmed.vt.edu/Curriculum/VM8054/Labs/Lab17/Images/digl10.jpg
Papillae of the TonguePapillae ofthe tongue
Num-ber
Locat-ion
shape Tastebuds
Kerat-inized
Serousglands
Inner-vationof tastecells
Func-tion
FiliformPapillae
majority anterior 2/3of thedorsum ofthe tongue
slenderthreadlike 2-3mm long
no tastebuds
yes no no give theroughmastica-torysurface ofthe tongue
Fungi-formPapillae
few, morenumerousnear thetip of thetongue
inter-spersedbetweenfiliform inthe anterior2/3
mushroomshaped
on thesuperiorsurface
no no Chordatympani
taste
Circum-vallatePapillae
10-14 Justanterior tothe V-shapedsulcusbetweenthe bodyand thebase of thetongue
large 3mm indiameter witha surroundingtrench
on thewalls
yes VonEbner’sglands
Glosso-pharyngealnerve
taste
FoliatePapillae
4-11 Lateralposteriorpart of thetongue
verticalgooves orfurrows
on thewalls
yes yes Glosso-pahryngealnerve
taste
Taste buds Barrel-shaped organs in epithelium Neuroepithelial vs. epithelial cells associated
with sensory nerve endings Chemical response Rapid turnover/ 10 days
Taste buds
Location Tongue
associated with the papillae Soft Palate Pharynx Epiglottis Larynx
Taste Buds Taste Pore Cell types (10-14/bud)
Supporting Cells (sustentacular cells) Taste Cells
Type 1(dark) Type 2 (light) Type 3
Basal cells Type 4 Precursors
Taste buds
Taste buds
Taste buds
Taste sensations 4 types
Sweet Salt Sour Bitter
Regional Sensitivity Role of
Oder/olfaction Temperature
Innervations of taste Buds Chorda tympani of facial nerve
Fungiform papillae Glossopharyngeal nerve
Vallate and foliate papillae soft palate pharynx
Vagus nerve Epiglottis Larynx
Innervations of lingual taste buds
www.biology.eku.edu/RITCHISO/ tastebud.html
Nerves and blood vessels Submucosa
Primary plexus of larger vessels and nerves Lamina Propria (dermal papillae)
Secondary plexus of terminal nerve endings and capillary loops
Encapsulated touch and temperature endings Axons associated with Merkel’s cells
Epithelium Avascular Free endings associated with pain
Nerves and Blood Vessels
online-media.uni-marburg.de/ .../HIS/txt/skin/skin02.htm
