oral mucosa structure Flashcards
what types of oral muccosa are there? and where do they line?
- Masticatory mucosa
- (15% of total area)
- Lining mucosa
- (60% of total area)
- Specialised mucosa
- (25% of total area)
what are the layers in epithelium during epithelium renewal?
what cells does the basal layer of epithelium contain? and what functions do they have?
Progenitor –
- amplifying cells for differentiation
Stem cells –
a division to produce a daughter cell and a progenitor
- Stem cells can renew themselves and form progenitor cells for differentiation
what is turnover speed of epithelium controlled by?
- locally produced cytokines/growth factors
describe the basal layer of oral epithelium
- Single layer on basal membrane
- Cuboidal or Columnar
- Interface of epithelia and lamina propria
- Contains most mitotic cells
- Precursor (proliferation and differentiation)
- Stem cells (Less proliferation and producing daughter cells)
- Producing K5 and K14
describe the spinous layer of oral epithelium
- Many cells thick
- Polyhedron like
- Cell proliferation close to basal layer
- Cells connections (Prickles)
- Cells have prickles on cell surface to connect cells
- Tonofibrils attached to desmosomes
- Keratins produced as non-secreted and insoluble proteins (K1, K6, K10, K16)
describe the granular layer of the oral epithelium
keratinised
- >3-5 cells thick
- Cells are flattened
- Highly keratins aggregated with tonofillaments to form tonofibrils bundles
- Intracellular fibre bundles
- Membrane-coating glycolipid form elongated granules
- More Cytokeratins accumulated on cell membranes
- Protein cross linked by TG1, 3 and 5
- Transglutamine 1 , 2 , 5
describe the keratinised layer of the oral epithelium
- Away from nutrients supply
- More flattened dead cells
- Lost cell nuclear and granules
- Full of keratin fibre through out the cells
- Wear off
what keratins are in non-keratinised epeithelium?
K5, K14, K19 and K4, K13
what keratins are in keratinised epithelium?
K5, K14 and K1, K2, K6, K10, K16
compare the composition of keratinised and non-keratinised epithelium?
how are epithelial cells connected?
- tight junctions
- gap junctions
- desmosomes
characteristics of tight junctions
- impermeable junctions
- prevents proteins passing through intercellular space
- uses ocludin, claudin and junctional adhesion molecules to seal intercellular space
characteristics of gap junctions
- has intercellular channels
- allows small molecules to transport to neighbour cells
- channel is made by 6 connecting proteins
characteristics of desmosomes
- connection used in protein anchoring
what are hemi-desmosomes?
Connect cell to the basal membrane
Mainly use integrin alpha 6 beta 4 as key protein to bind extracellular basal lamina protein - called lamina lucida
What are Merkel cells
where are they found?
- Situated in basal layer of epithelium
- Not dendritic like
- Express tonofilaments and keratins
- Desmosomes linked to adjacent cells
- & hemidesmosome connection to basal layer
- Containing small granules adjacent to the synapse connection with nerve fibre
- Sensory and respond to touch
what are melanocytes
where are they found
roles?
Situated in basal layer of epithelium
Self renewing pigment cells
Arise from the neural crest ectoderm
Enter epithelium about 11 weeks of gestation
Long dendritic branching in between keratinocytes
Same numbers of melanocytes in darker or lighter skin persons, but the levels of melanin producing various.
what are langerhans cells?
where are they found?
role?
- Type of resident macrophages
- Derived from yolk sac in embryo
- Self renew and dividing in epithelium
- Migrating out of epithelium
- Become this :
- Antigen presenting cell for T cell activation
- Become this :
What are the immune cells in oral epithelium?
CD8+T and NK cells
Are transient and not reproducing
Related to inflammatory responses
In normal mucosa, they may play a role of immune tolerance
Memory T and B cells capable to responding quickly to antigenic challenge
what is the lamina propria?
characteristics?
Thin layer of loose connective tissue –rich in elastic fibre and collagen fibres
Under epithelia basement membrane
- Loose and rich in cells
- Blood vessels and nutrition supply
- Lymphoid vessels for drainage, lymphoid tissue
- Antigen presenting cells drainage
- Glands and ducts open to epithelial
- Can be found in lamina propria
- Rich in immune cells for defence, also maintains tolerance to the insults
what cells are in the lamina propria?
Fibroblast
Dendritic cell
Macrophage
Mast cell
Leukocytes (T and B cells)
Plasma cell
Endothelial cell
how is the properties of the oral gingival epithelium able to cope with the environment it is in?
it is exposed - must cope with mastication
- keratinised stratified squamous epithelium
- deep rete ridges
- may provide a fast turnover rate - hosts more stem and progenitor cells
where is oral sulcular epithelium
what kind of epithelium and what properties?
- SE extends from the gingival margin into the sulcus
- SE is protected inside the gingival crevice and so is a non-keratinised stratified squamous epithelium without (significant) Rete pegs
- Makes more permeable
- GCF
- Makes more permeable
where does junctional epithelium originate from
from reduced enamel epithelium in tooth eruption
what is the role of the junctional epithelium?
responsible for attaching gingiva to tooth surface
what is the junctional epithelium composed of?
Stratified squamous epithelium, internal & external basement membranes
role of hemidesmosomes in junctional epithelium
Uses hemidesmosomes to attach internal and external basal membrane
- Internal covers cementum and enamel
- External covers gingival connective tissues
Attachments to ‘tooth’ (cementum) and ‘gingival connective tissues (Lamina Propria) are mediated by hemidesmosomes
