Oral Mucosa Flashcards
What type of epithelium does the oral mucosa consist of?
Stratified squamous epithelium (both keratinized and non-keratinized)
How does the type of illness affect the way the illness look in the oral cavity?
When there is increase in sickness the epithelium looks whitish.
When there is a decrease in sickness the epithelium looks less white.
This is due to keratin layer being affected. (Eg. squamous cell carcinoma)
What are the roles of the oral mucosa?
It is protective against both compressive and shearing forces
Barrier function
Immunological defense
Lubrication, buffering, and secretion of antibodies
Input for touch, proprioception, pain, and taste (highly innervated
What are the 3 components of the oral mucosa?
Epithelium
Lamina propria
Sub-mucosa
What body system is the oral mucosa a part of?
Oral mucosa is part of the mucosa covering the alimentary tract
What are the histological layers of the oral mucosa?
Oral epithelium
Basement membrane
Lamina propria consisting of basal and papillary layer + a dense fibrous layer
Submucosa
How is epithelium attached to the connective tissue?
By a basement membrane and they are attached to each other.
Where is epithelium derived from embryologically?
Ectoderm or endoderm.
What does the lamina propria consist of?
Dense connective tissue
Submucosa (looser connective tissue)
What happens if the adhesive junctions in oral mucosa is defective?
This leads to a condition called pemphigous. Defect is seen between cells.
How is pemphigous treated?
Via use of corticosteroids
What causes pemphigo?
Pemphigo occurs when anchoring fibrils are defective between the cells of the basement membrane and reticular fibers.
What are the layers of the epithelium of the oral mucosa?
Stratum germinativum
Stratum spinosum
Stratum granulosum
Stratum corneum
What are the types of layers of epithelium?
Pyknotic layer
Maturing layer
Basal layer
Basement membrane
What cells are seen in the stratum germinativum/basale?
Single cell layer adjacent to the lamina propria
Cuboidal cells, progenitor cells, give rise to cells in epithelial cells above
A minority are true stem cells
Non-keratinocytes may be found in the stratum germinativum
Why does the oral mucosa heal faster than the rest of the body?
Because of the quality of the cells in the stratum basale (mitotic index high)
What happens in the stratum spinosum?
Consists of round or ovoid cells
First stages of maturation is present here from the stratum basale. They are rounder and larger than the startum basale.
Desmosomes
Parabasal layer is the layer adjacent to the basal layer
What is contained in the stratum granulosum?
Many organelles are reduced or lost, cells are larger and flatter/ Contain keratohyaline granules.
Membrane-coating granules discharge into the extracellular space.
Development of a barrier in the epithelium that limits the movement of substances between the cells.
What is contained in the stratum corneum?
Final stage of maturation
Epithelial squamas (shed via desquamation)
Mechanical protective function to the mucosa
Ortho or parakeratinized
In lining epithelium the epithelial cells are non-keratinized at the surface
What is the principle cell in the oral epithelium?
The keratinocyte which are rapidly renewing, terminally differentiated cells with cytoplasmic filaments, cell envelopes, and specialized cell junctions
What are cytokeratins?
a type of intermediate filament
What si the cytoskeleton composed of?
Micro and intermediate filaments
Microtubules
Why are cytokeratins so important?
Cytokeratins are specific to different types of epithelium and this is useful because antibodies can be used to visualize these layers
How many cells of the oral epithelium are non-keratinocytes?
Up to 10%
What are Langerhan cells?
Bone marrow derived dendritic cells which present antigenic informatin to T-suppressor lymphocytes
How is the oral mucosa of different races different in colour and why?
Larger number of melanocytes present in the oral mucosa of darker skinned people making the mucosa appear darker
What is the most dangerous tumour that can affect the oral cavity?
Melanomas
Where do melanocytes arise from embryologically?
They are neural crest cells.
What are granstein cells?
similar to Langerhans cell but present antigenic information to t - helper lymphocytes
What are merkel cells?
epithelial neural cell found in basal
layer containing vesicles and filaments, a
sensory receptor
What is a melanocyte?
dendritic cell of neural crest origin
forming a continuous network in the basal layer
What do langerhan cells do?
APCs
Contact hypersensitivity reactions
Anti-tumour immunity
Graft rejection
Birbeck granules
What are the layers of the lamina propria?
Superficial papillary layer
Collagen fibres are thin and loosely arranged
Deep, reticular layer: Thick, parallel bundles of collagen
fibres
Collagen – 90 % type I, 8% type III, non - fibrous forms of collagen .
Elastin
fibres
.
What do fibroblasts do?
synthesize and degrade the extracellular
matrix, interact with epithelium, important for wound
healing
What do mast cells do?
large polygonal cells containing
metachromatic granules, involved in inflammation and
immune response
What immune cells are present in the lamina propria?
macrophages, polymorph neutrophils and
lymphocytes may be present
What peripheral nerve cells are present in the lamina propria?
Sensory, Schwann cells and various nerve endings
What is the role of the basement membrane?
Important role in attachment of epithelium to connective tissue
When there is a breach of this membrane there is a carcinoma (helps with staging)
How does the structure of the oral mucosa vary?
Thickness of the epithelium
Degree of keratinisation
Complexity of the connective tissue
Composition of the lamina propria
Presence or absence of the submucosa
What are the types of mucosa?
Lining mucosa
Masticatory mucosa
Tongue mucosa
Where is non-keratinising mucosa located?
Buccal mucosa
Labial mucosa
Soft palate
Floor of the mouth
Gingival sulcus
Ventral surface of tongue
Junctional epithelium
Alveolar mucosa
Where is keratinising oral mucosa located?
Dorsal surface of the tongue
Gingiva
Hard palate
What percentage of oral epithelium is non-keratinized?
10% of epithelium is non-keratinized
What kind of mucosa does the buccal mucosa contain?
Thick non-keratinized epithelium
Lamina propria is dense
Submucosa contains minor salivary glands
Fordyce spots
What are the zones of the lip?
Outer surface (Skin)
Inner surface (Labial mucosa)
Vermilion zone (Red or transition zone)
What are the unique features of the outer surface of the lip?
Contains keratinized epithelium
Sweat glands
Sebaceous glands
Hair follicles
What are the features of the vermilion zone?
Keratinized epithelium - thin and translucent
Sebaceous glands (very occassionaly may be found (angles of the mouth especially))
Connective tissue papillae are long, narrow and contain capillary loops
Intermediate zone is parakeratinized
How many minor salivary glands are present in the submucosa?
600 to 1000 minor salivary glands
What are the features of the labial mucosa?
Thick non - keratinized epithelium • Lamina propria is wide , the papillae are short and irregular . • Submucosa – minor salivary glands
Small muscles
What is the labial frenum?
The protrusions of gums between the gum linign and the lower lip (labial side)
What are the important functions of the soft palate?
Sound production
Mastication
What are the features of specialized mucosa and where is it located?
• Is a specialized region of gustatory mucosa . • Keratinized epithelium + thick lamina propria • The dorsum of the tongue
Specialized mucosa is found on the dorsal surface of the tongue where the epithelium and connective tissue is either arranged into large papillae or other structures
Where are circumvallate papillae located?
In a junction between anterior 2/3ds and posterior 1/3rd of the tongue
What happens to mucosa overlying absent teeth in edentulous patietns?
The friction generated
by mastication in the absence of
teeth often results in frictional
keratosis of the mucosa
What does edentulous mean?
Lacking teeth
