oral mucosa

what is the stomodeum lined by

ectoderm

what type of epithelium is the oral cavity

stratified squamous epithelium (so it the epidermis- skin)

the oral mucosa and submucosa types are all dependent on:

location: whether it be inside the area of mastication or outside the area of mastication

what are characteristics (4) of oral mucosa/submucosa that are INSIDE the area of mastication

• masticatory mucosa

• keratinized epithelium

• highly fibrous reticular layer

• bone

what are characteristics (4) of oral mucosa/submucosa that are OUTSIDE the area of mastication

• lining mucosa

• non-keratinized epithelium

• normal reticular layer

• muscle

in what ways are features of masticatory mucosa and lining mucosa similar to our skin

• have keratinized epithelium

• normal reticular layer

• attach to muscle

what type of mucosa is represented by the BLUE highlighted areas/arrow and how much surface area does it take up

lining mucosa- 60%

what type of mucosa is represented by the RED highlighted areas/arrow and how much surface area does is take up

masticatory mucosa- 25%

what type of mucosa is represented by the green highlighted area/arrow and how much surface area does it take up

specialized mucosa- 15%

what are the functions of the oral mucosa

• mechanically protective against compressive and shearing forces

• provides innate immune barrier to microorganisms, toxins, antigens

• immunological defense both innate and adaptive

the oral mucosa is richly innervated providing what type of sensory outputs

modalities of:

• touch

• proprioception

• pain

• temperature

• taste

salivary glands within the mucosa secrete saliva, what are some components that make up the saliva

• lubricating and buffering

• antibodies- sIg’s

• germicides

the mucous film from saliva has what role in the oral cavity

acts as a barrier helping to retain water and electrolytes, keeping the oral cavity moist

what structure in the oral cavity is the first site to encounter inhaled/ingested microorganisms and is considered the first line of adaptive immune defense against pathogens

palatine tonsils

what type of tissue are the palatine tonsils

lymphatic tissue → mucous associated lymphoid tissue (MALT)

what are germinal centers and where are they found

in palatine tonsils: represent activated (antigen presented) B-cells becoming antibody producing plasma cells

nodules are filled w…

B cells

what are the 3 general layers of lining/masticatory mucosa from superficial to deep

1. epithelium- stratified squamous

2. lamina propria

3. submucosa → NOT in masticatory

epithelium of masticatory mucosa has what origin

ectodermal origin

generally, what can be found in the epithelial layers masticatory/lining mucosa

• keratinocytes- 90% of cells

• exocrine glands ducts

• non-keratinocytes- 10% of cells

what cells are non-keratinocytes that are found in the epithelium (4)

• melanocytes

• langerhans cells

• merkel cells

• nerve endings

origin of melanocytes

neural crest

origin of langerhans cells

monocytes

origin of merkel cells

ectodermal

origin of nerve endings

neural crest

origin of lamina propria

ectomesenchyme

generally, how do the lamina propria layers between lining mucosa and masticatory mucosa differ

• in lining: lamina propria and submucosal layer have no keratinized tissue, JUST LIKE OUR SKIN

• masticatory: has keratinized tissue, lots of dense fibers

what is included in the submucosal layer of lining mucosa

• exocrine glands

• adipocytes, connective tissue

origin of exocrine glands in submucosal layer of lining mucosa

ectodermal

origin of adipocytes, connective tissue in submucosal layer of lining mucosa

ectomesenchyme

lining or masticatory mucosa

lining mucosa

lining or masticatory mucosa

masticatory mucosa

lining mucosa is _________ (soft/firm) and ___________ (pliable/immobile)

soft and pliable

masticatory mucosa is _________ (soft/firm) and ___________ (pliable/immobile)

firm and immobile

bc lining mucosa is soft and pliable, what properties does this lead to when it comes to injections/injury

• fluids easily injected

• lining gapes when cut→ won’t tear or fall apart

• inflammation is dispersed→ won’t rlly hurt

bc masticatory mucosa is firm and immobile, what properties does this lead to when it comes to injections/injury

• injections are painful

• lining tears when cut→ bc not enough space to expand

• inflammation is painful

prior to tooth eruption, the epithelium is either _______________ or ______________

para-keratinized or non-keratinized

para-keratinized epithelium differs from keratinized epithelium in what (3) ways:

• basophilia of the outermost layers bc of nuclei present

• absence of a distinctive stratum granulosum

• absence of stratum corneum

what type of epithelium is this

parakeratinized epithelium

what type of epithelium is this

lining mucosa- nonkeratinized epithelium

when does keratinized stratified squamous epithelium develop

during primary tooth eruption

what type of epithelium is this

masticatory mucosa- keratinized epithelium

what is the main funx of the basal layer

to undergo mitosis for either self renewal or to replace differentiated cells above the basal layer

are keratinocytes or non-keratinocytes derived from the basal cell layer

• keratinocytes → generalized term for all cells derived from basal cell layer

• non-keratinocytes → non derived from basal cell layer

what are the two filament types of the cytoskeleton in epithelial cells

• microfilaments

• intermediate filaments

what type of filaments are the microfilaments, what size are they

actin filaments; 7 nm in diameter

what type of attachments do actin filaments have

have adherent junctions and focal adhesions

function of actin filaments

allow movement of cell surface, enabling cells to migrate, engulf particles, and divide

what type of filaments are intermediate filaments and what size are they

keratin filaments; 10 nm in diameter

what do keratin filaments attach to

• desmosomes

• hemidesmosomes

are actin or keratin filaments larger

keratin filaments

funx of keratin filaments

more structural support; provide mechanical strength to cells and tissues

desmosome funx w keratin filaments

major contributor: help w side-to-side tension

hemi-desmosome funx w keratin filaments

hold onto basal cells and underlying CT

what are the two kinds of keratin fibers you can find in the oral epithelium

keratins:

• neutral/basic

• acidic

which keratins are neutral/basic

CK1-CK9

which keratins are acidic

CK10-CK20

cytokeratins always occur in pairs…

one neutral and one acidic

what are the cytokeratins in masticatory mucosa

CK1 and CK10

what are the cytokeratins in lining mucosa

CK4 and CK13

what are the cytokeratins in the soft palate

CK 7, 8, 18

what are the cytokeratins that make up the basal layer

CK5 and CK14

loss of keratin ___ is one of the most valuable diagnostic criteria for discriminating carcinoma in situ from non malignancies in the oral mucosa

keratin 13

why is keratin 13 used to distinguish malignant lesions

is stable in the prickle cells of normal epithelium, and will be lost in a cause of neoplasms

what are the four layers of keratinized epithelium is masticatory mucosa from superficial to deep

1. keratinized layer

   • stratum corneum

2. granular layer

   • stratum granulosum

3. prickle cell layer

   • stratum spinosum

4. basal layer

   • stratum basale

what is going on in the basal layer of keratinized epithelium

• desmosomes

• keratin filaments form tonofibrils

• cell divisions

• hemidesmosomes→ hooked to basement membrane

what is going on in the prickle cell layer of keratinized epithelium

• keratin fibrils→ from keratin filaments wrapping and building onto each other

• desmosomes increasing in attachments to neighbor

• formation of membrane-coating granules

what is in the granular layer of keratinized epithelium

• keratin fibrils

• desmosomes

• keratohyalin granules forming

• secretion of glycolipids from membrane coating granules

  • MCG also being pushed to the outside of the cell to make room for the keratohylain granules

what is in the keratinized layer of keratinized epithelium

• all cell organelles lost

• formation of the “cornified envelope”

  • glycolipids opening up

  • keratinohylaine granules opening up

  • heavy fibril network extending completely into the internal cytosol

what happens in the keratinized layer when glycolipids start to open up

these will coat the cell in a hydrophobic material and will contribute to the toughness of the plasma membrane

what happens in the keratinized layer when the keratohyalin granules are opening up

it’s contents are keratin filament associated proteins/binding proteins, and these will aid in locking the keratin fibrils together

what are the keratin filament associated proteins (KFAP, binding proteins) that are released from keratohyalin granules

• filaggrin

• loricrin

• involucrin

where is filaggrin

synthesized in the granular layer and stored in keratohyalin granules; is the main contributor

funx of filaggrin

binds to and condenses the keratin cytoskeleton and thereby contributes to the cell compaction process that creates the squamous cell shape

where is loricrin

expressed in the superficial layers of keratinized and nonkeratinized oral epithelia

funx of loricrin

binds to the ends of keratin and contributes toward cornification

funx of involucrin

binds to loricrin and helps to create the cornified envelope

what areas can show variation of keratinized and parakeratinized

parts of hard palate and much of the gingiva

what causes parakeratinization

due to incomplete removal of organelles from the granular layer

what are the 4 layers of non-keratinized epithelium from superficial to deep

1. surface layer

   • stratum superficiale

2. intermediate layer

   • stratum inermedium

3. prickle cell layer

   • stratum spinosum

4. basal layer

   • stratum basale

how does the basal layer of nonkeratinized epithelium compare to keratinized epithelium

no difference:

• desmosomes- maybe fewer

• keratin filaments

• cells division

what is the difference between the prickle cell layer of keratinized vs nonkeratinized epithelium

no desmosomes, both will have:

• keratin filaments

• membrane-coating granules

what is in the intermediate layer of nonkeratinized epithelium

glycogen vesicles

what is in the surface layers of nonkeratinized epithelium

incomplete removal of organelles → cells are still alive!

what is the purpose of having glycogen vesicles in the intermediate layer of non-keratinized tissue

nutrients will be diffusing from basal layer, but this mode is insufficient for cells that are still alive in the surface layer compared to keratinized tissue, where you usually do not worry ab bc they are dead. glycogen vesicles supply nutrients for live cells that are in the surface layer

what are melanocytes

contain the pigment melanin

what layer can melanocytes typically be found

in basal layer

what is melanin packaged into

melanosomes

how is melanin formed

through the oxidation of tyrosine—DOPA—melanin

cytoplasmic extensions establish contacts with over ____ keratinocytes

30

melanosomes are ‘injected’ into oral keratinocytes, what is the funx of this

to form a protective shield against UV-radiation

what are Langerhan cells

antibody to’ lamgerin’ L cell protein; antigen presenting, dendritic cell that will present antigens to T cells, also play a role as macrophages

langerhan cells are derived from…

bone marrow- monocytes

what layer are langerhan’s cells present, why

in stratum spinosum → will scan the epithelium for antigens

characteristics of langerhan cells

motile → have no desmosome attachments to keratinocytes to be able to migrate to regional lymph vessels

what layer can merkel’s cell be found

has desmosomal attachments to basal layers of epithelial cells

precursor to Merkel’s cell

are differentiated basal cells

what do cytoplasms of Merkel’s cell contain

• keratin filaments → CK20

• small granules containing neuropeptides → SP, ViP

characteristics of Merkel’s cells

• slowly adapting mechanoreceptor- touch

• abundent in hard and soft palate, mandibular gingiva

how do Merkel’s cell respond to inflammation

• will inc in acute inflammation

• will jump substantially in number in chronic inflammation