OE L19 Oral Mucosa: Histological Structure and Function Flashcards
What is the oral mucosa?
The mucous membrane lining the oral cavity.
Comprises:
- Stratified squamous epithelium
- Lamina propria (underling CT)
Is the epithelium vascularised?
No it is avascular, so the lamina propria supplies nutrients to it and removes waste.
What does the junction between the epithelium and lamina propria look like?
The epithelium has finger like projections into the lamina propria called rete ridges.
This creates a larger SA for diffusion of nutrients and removal of waste, and gives good mechanical strength thus preventing shearing of the epithelium.
Type of oral mucosa differs dependent on location, what are the 3 types and where are they found?
- Keratinised mucosa (masticatory mucosa): found in areas of highest friction e.g. gingivae and hard palate
- Specialised mucosa: found on dorsum of the tongue
- Non-keratinised mucosa (lining mucosa): rest of the oral cavity e.g. cheeks
How do keratinised and lining mucosa appear clinically and histologically?
Keratinised mucosa:
- Tightly bound to underlying alveolar bone
- Whiter in appearance
- Histologically: keratinised, high collgen content
Lining mucosa:
- Loosely bound, softer and stretchier
- Redder appearance
- Histologically: non-keratinised, high elastin content
What are the 4 layers of an epithelium?
- Stratum corneum = superficial cell layer
- Stratum granulosum = intermediate cell layer, contains lots of granules
- Stratum spinosum = spine like cells
- Startum basale = basal layer, bottom layer with actively dividing cells
What are the 8 key functions of oral mucosa?
- Barrier against mechanical damage
- Barrier against permeability
- Sensation (temp, touch, pain)
- Secretion from minor SGs
- Thermal regulation
- Special sense (taste)
- Defence (turnover immune system products)
- Adaptation (healing, friction)
Oral epithelium is subject to changes, give examples of types of changes.
- Genetic
- Physical e.g. chewing
- Chemical e.g. food and drink
- Infection
- Auto-immune
- Metabolic
Name 5 types of responses of the oral epithelium to external/internal factors.
- OE can be lost in areas and expose underlying CT (ulcer, more shallow=erosion)
- OE may thicken to create protective barries (white area=keratinisation)
- OE may get thinner, seen as red area due to underlying CT
- Metaplasia (change in cell type e.g. lining mucosa may start to produce keratin) or dysplasia (presence of abnormal cells, usually pre-cancerous)
- Seperation of epithelium
Describe aphthous ulceration.
- Common (10-20% of population)
- Small regular ulcers
- Painful
- Take 4-5 days to heal
- May appear white, means it is healing and fibrin present
Describe pemphigus vulgaris.
- Ulcerative condition
- Not restricted to oral cavity
- Bolus condition (bubble), uncommonly seen as bubble in practice as it bursts
- Partial seperation of epithelium from CT
- Uncommon
- Red appearance
Autoimmune, intraepithelial, blistering disease affecting skin and mucous membranes
Describe mucous membrane pemphigoid.
- Blistering condition
- Differs from pemphigoid vulgaris as there is a clean split between OE and underlying CT
- Commonly affects gingivae, palate and buccal mucosa
- Antibodies present at junction between OE and CT
Describe herpes.
- Viral infection
- Triggered by range of factors including sunlight, trauma, stress
How is epithelial renewal controlled?
Interactive expression of growth factors and receptors.
State of homeostasis created of cell formation and loss.
What is the term used to describe the shedding of the top layer of epithelium?
Desquamination
