OB P1 - Oral mucosa Flashcards
What are the 2 basic tissues of oral mucosa?
– epithelium (superficially) (tightly packed)
– connective tissue (underlying)
What is the role of oral mucosa?
> Protection – mechanical – bacterial – chemical – prevent dehydration (barrier)
> Secretion
thermal regulation
Describe the sensation of oral mucosa?
richly innervated
Describe the oral mucosa layers from the teeth up.
- Free gingiva
- attached gingiva
- alveolar mucosa
what junction is between alveolar mucosa and attached gingiva?
Mucogingival junction
What are the 3 main types of mucosa in the mouth?
- Masticatory (tough , around the teeth and hard palate)
- Lining mucosa
- Specialised (dorsum of the tongue - receptors for taste)
What are the layers of non-keratinised lining mucosa?
- Epithelium
- Lamina propria
- submucosa
- bone or muscle
Where is non-keratinsed lining mucosa found?
Inside the lips, alveolar mucosa, floor of the mouth, soft palate , buccal mucosa
Describe the features of non-keratinised lining mucosa.
- Undulating interface with lamina propria
- few rate pegs
- Lamina propria and submucosa
- no muscularis mucosae
- flexible
- not subjected to high stress
Name the layers of the epithelium of non-keratinised lining mucosa.
- Superficial layer
- intermediate layer
- Prickle cell layer
- basal cell layer
Name the layers of the epithelium of non-keratinised lining mucosa using terms used in Berkovitz et al.
- Stratum superficiale
- Stratum intermedium
- Stratum spinosum
- Stratum germinativum
How did the prickle cell layer get its name?
When you fix a tissue -shrinkage occur
-Cells shrink but they are still attached by desmosomes so have prickly appearance
What do all epithelial cells have?
- filaments
- desmosomes
Describe basal cells (lining mucosa).
- Least differentiated
- mitosis often visible
Describe prickle cells (lining mucosa).
Membrane coating granules (MCGs)
Describe the intermediate layer (lining mucosa).
MCGs discharge contents between cells:
- permeability barrier
- not wholly effective
What is the clinical importance of MCGs discharging its contents between cells?
-Drugs absorbed such a sublingual GTN sprays for angina (rich blood supply to oral mucosa so it is rapidly absorbed and pain goes away)
Describe the superficial layer (lining mucosa).
- flattened cells
- nuclei persist
- not dehydrated so flexible
Why are superficial cells in lining mucosa alive?
Nutrients from the basal layer come through the spaces to the superficial layer
What are the layers of keratinised masticatory mucosa?
- Epithelium
- lamina propria
- periosteum
- bone
What are the 2 layers of lamina propria?
- papillary layer
- reticular layer
Describe the features of keratinised masticatory mucosa.
- many rete pegs /ct papillae
- no submucosa
- thick lamina propria
- lamina propria firmly anchored to bone
- resistant to compression
- relatively immobile
- mechanically tough
Describe the difference in the sensation of local anaesthesia between lining mucosa and masticatory mucosa.
- Lining mucosa - flexible - can be pain free if done properly
- Masticatory mucosa -tightly bound down - can hurt
Name the layers of the epithelium of keratinised masticatory mucosa.
- Keratinised layer
- granular layer
- prickle cell layer
- basal cell layer
Name the layers of the epithelium of keratinised masticatory mucosa using terms used in Berkovitz et al.
- Stratum corneum
- Stratum granulosm
- Stratum spinosum
- tratum germinativum
Describe the basal cells (masticatory mucosa).
like non-keratinised epithelium
Describe the prickle cells (masticatory mucosa).
filaments organised into bundles -tonofibrils
Describe the keratohyaline granular in the granular layer cells (masticatory mucosa).
Keratohyaline granules:
- 0.5 to 1 microns
- associated with tonofibrils
- filaggrin (forms matrix for filaments in keratinised layer)
Describe the MCGs in the granular layer cells (masticatory mucosa).
MCGs discharge contents sealing cells together :
- effective permeability barrier
- cells beyond this barrier zone are de-hydrated
(-stuff from outside will not get beyond this layer i.e drugs
-also nutrients dont get to keratiniased cells (so they are dead)
Describe the keratinised layer (masticatory mucosa)
- Flattened cells - “squames”
- no organelles
- contain filled with keratin
- dehydrated -not flexible
What is para-keratinised?
Incomplete removal of organelles from the superficial layers :
-nuclei shrunken -pyknotic
What is epithelial turnover?
From cell dividing to cell being lost (i.e basal to shed)
What is the epithelial turnover for junctional epithelium?
5 days
What is the epithelial turnover for the cheek?
10-14 days
what epithelial turnover is slower?
masticatory mucosa
what is the speed of healing process?
rapid ( no scarring in the mouth)
Describe the epithelial abnormalitie acanthosis.
– Hyperplasia of the prickle cell layer
– e.g. psoriasis
Describe the epithelial abnormalitie acantholysis.
– Disruption of intercellular connections
– e.g. pemphigus
what are keratinocytes characterised by?
– Tonofillaments
– Desmosomes
How many cells within the epithelium are keratinocytes ?
90%
what make up the other 10% of cell in epithelium?
Non-kerartinocytes - “clear cells”
What do non-keratinocytes lack?
tonofilaments and desmosomes
what do non-keratinocytes include?
– Merkel cells
– Melanocytes
– Langerhan’s cells
– Inflammatory cells
Why do non-keratinocytes appear clear under light microscopic appearance?
After fixing, the cells shrink and with no desmosome attachments they do not stay attached to neighbouring cells and look like a clear space
What are the 2 types of clear cells in a basal layer?
-Merkel cells :
touch receptors
-Melanocytes :
dense melanosomes
melanin
what is the degree of pigmentation due to?
Due to the activity of melanocytes , not the number (everyone has a similar number of melanocytes )
What are the 2 types of suprabasal layer clear cells?
- Langerhans cells
- Inflammatory cells
Describe langerhans cells.
- In more superficial layers
- Dendritic
- Process antigenic material
Describe inflammatory cells.
- transiently migrate into epithelium
- lymphocytes common
what structures are found between the epithelium and the connective tissue papilla?
Rete peg
Describe the epithelium-lamina propria interface.
Large surface interface area: – disperses applied forces
– metabolic interchange
what is controversial about rate pegs?
Is it pegs of epithelium in connective tissue? OR
Is it pegs of connective tissue in epithelium? OR
Is it folding?
What is in the basal lamina?
- Basal cell
- hemi-desmosomes
- lamina lucida
- lamina densa
- anchoring filaments
- collagen fibrils
- anchoring fibrils
what are the 2 layers of the basal lamina?
-Lamina lucida :
>45nm thick
>glycoprotein -laminin
-Lamina densa:
>50nm thick
>type IV collagen and laminin
What is found in the lamina propria?
- Collagen: > 90% type I >8% type III - Loose in papillary layer - More organised in the reticular layer - Fibroblasts - Defence cells
What is the sensory innervation of connective tissue?
– free nerve endings
– krause end bulbs
– ruffini corpuscles
What is the sensory innervation in epithelium?
– free nerve endings
– Merkel cell ‐ neurite complexes
