DHY121 Oral MUCOSA & Oral EPITHELIUM

oral mucosa

the lining of a body cavitythat opens to the outside of the body

main function of oral mucosa

forms a protective barrier against various injurious stimuli

additional functions of the oral mucosa

1. secretions

2. sensory

what does the oral mucosa secrete and what is it for?

saliva; lubrication that contains antimicrobial agents

what senses can the oral mucosa feel?

touch, pressure, pain, & temp preception

both skin and oral mucosa are composed of what two tissues?

surface epithelium & underlying connective tissue layer

what are the oral mucosa’s surface epithelium and underlying CT layer?

• surface epithelium = oral epithelium

• underlying CT layer = lamina propria

what are the skin’s surface epithelium and underlying CT layer?

• surface epithelium = epidermis

• underlying CT layer = dermis

the layer underneath the lamina propia and dermis:

• under lamina propria: sub mucosa

• under dermis: hypodermis

the different types of oral EPITHELIUM found in the oral cavity:

1. orthokeratinized stratified squamous epithelium

2. parakeratinized stratified squamous epithelium

3. nonkeratinized stratified squamous epithelium

the different types of oral MUCOSA found in the oral cavity:

1. masticatory mucosa

2. lining mucosa

3. specialized mucosa

masticatory mucosa is made up of what layers:

1. keratinized stratified squamous epithelium

2. lamina propria

3. bone

lining mucosa is made up of what layers:

1. nonkeratinized stratified squamous epithelium

2. lamina propria

3. submucosa

4. muscle

specialized mucosa is made up of what layers:

1. stratified squamous epithelium

2. lamina propria

3. tongue muscles

where can masticatory mucosa be found?

• gingiva

• hard palate

where can lining mucosa be found?

• alveolar mucosa

• soft palate

• labial mucosa

• buccal mucosa

• tongue (ventral)

• floor of the mouth

where can specialized mucosa be found?

• tongue (dorsal)

function of masticatory mucosa

immovable relative to underlying tissue, resistant to compression

function of lining mucosa

movable relative to underlying tissue, compressible, reflective, flexible

function of specialized mucosa

contains specialized appendages (lingual papillae); taste

the alveolar mucosa is considered to be a lining mucosa but…

does not have a sub mucosa

lining mucosa is often thin except for….

• labial mucosa

• buccal mucosa

rete pegs/CT papillae of the masticatory mucosa are:

• highly corrugated

• numerous amount

• tall, narrow

rete pegs/CT papillae of the lining mucosa are:

• more/less corrugated

• variable amount

• short

• irregular/indistinct/absent

desmosomes

the stitching between two epithelial cells, mechanical attachment; permeable

hemisdesmosomes

the stitching between an epithelial cell and a non-cellular surface; found in basal layer; half of a desmosome

tight junction

two cell membranes fused together, forms a fluid tight barrier; less permeable

intermediate/gap junction

allows cells of a tissue to communicate w/ each other; when two cell membranes are closely opposed but do not adhere to one another; permeable

basement membrane

the interface/border of the epithelium and lamina propia

basement membrane composed of:

1. basal lamina

2. reticular lamina

basal lamina

product of basal cells of epithelium, consist of proteins & glycoproteins

reticular lamina

product of CT cells in the lamina propria from fibroblast/ anchoring fibrils; consist of fine collagen fibrils (fibrous proteins)

how does the basal lamina and reticular lamina adhere together?

though hemidesmosomes and anchoring fibrils

the basement membrane is what pattern?

corrugated

rete pegs

increases the surface area between the epithelium and lamina propria → increases mechanical support

CT papillae

increases the surface area from the capillaries of the lamina propria to the epithelium → increases biological support

mechanical support

greater area of attachment between the two tissues → makes the mucosa resistant to shearing forces

biological support

allows the exchange of nutrients from the capillaries since the epithelium is avascular and would depend on the CT for nourishment; permeable

what causes the stippling of the gingiva?

rete pegs & CT papillae

if the masticatory mucosa experiences with lots of mechanical loading, how many rete pegs & CT papillae would it have?

numerous amounts of both

why does the lining mucosa have a varied number of rete pegs & CT papillae?

it is moveable and compressible

stratified squamous epithelium

goes through a cycle of shedding surface cells and regeneration of the tissue; could have keratin

turnover rate for oral epithelium

4-24 days

turnover rate for skin

27 days

types of stratified squamous epithelium for masticatory mucosa

• orthokeratinized

• parakeratinized

type of stratified squamous epithelium for lining mucosa

• nonkeratinized

where is orthokeratinized stratified squamous epithelium found?

skin

where is parakeratinized stratified squamous epithelium found?

oral mucosa

the layers of the keratinized oral epithelium:

1. stratum basale

2. stratum corneum

3. stratum spinosum

4. stratum granulosum

the cell types corresponding to the layers of the keratinized oral epithelium:

1. basal cells

2. spinous cells

3. granular cells

4. cornified cells

basal cells characteristics

• cuboidal

• has a nucleus

• one single cell layer

• has lots of protein-synthesizing machinery

• has tonofilaments

the precursors of keratin

• tonofilaments

• keratohyaline granules

basal cell function

• secretes basal lamina for the BM

• provide hemidesmosomes of attachment point to the CT

• only dividing/replicating cells in epithelium

spinous cell characteristics:

• polyhedral cells

• the bulk/thickest layer of the epithelium

• prickly appearance due to being shrunk and maintaining the desmosomes

spinous cell function

• increases the number of tonofilaments

granular cell characteristics

• flatter, atrophy

• has keratohyaline granules & tonofilaments

• contains abundant organelles associated with keratin synthesis

• has a low number of keratin precursors

granular cell function

• form the granular layer of the oral epithelium

cornified cells characteristics

• extremely flattened

• cytoplasm is filled with keratin

• thickened cell membranes

• desquatmate (flake off)

cornified cells function

• forms the keratin layer of oral epithelium

roles of keratohyaline granules

• aggregation of tonofilaments into keratin which becomes apparent in the keratin layer

• thickening of the cell membrane

what layers are the same in both ortho and para keratinized epithelium

stratum basale and stratum spinosum

what layers are different in the ortho and para keratinized epithelium

stratum granulosum and stratum cornified

how does the orthokeratinized granular layer differ from the parakeratinized?

• very distinct layer, very thick layer

• has more keratohyaline granules

how does the orthokeratinized cornified layer differ from the parakeratinized?

• cornified cells do not have a nucleus or cellular organelles

• can not produce keratin

how does the parakeratinized granular layer differ from the orthokeratinized?

• not as distinct layer

• less keratohyaline granules

how does the parakeratinized cornified layer differ from the orthokeratinized?

• cornified cells still have their nucleus and organelles

• keratin is produced

the layers of the nonkeratinized epithelium:

1. stratum basale

2. stratum intermedium

3. stratum superficiale

stratum basale of the nonkeratinized epithelium

same as keratinized epithelium basal layer

intermediate layer

• apart of the nonkeratinized epithelium

• similar to spinous but…

• cells do NOT have a prickly appearance

superficial layer

• apart of the nonkeratinized epithelium

• replaces the granular and keratin layer

• contains cells that are flattened, fluid-filled, has their nucleus

cells that are non-keratinized:

• melanocytes

• langerhans cells

• merkel cells

keratinocytes

general term for any cell that produces keratin

merkel cell

• associated with fine tactile sensations (mechanoreceptors)

• found in epithelium of fingers and tongue

langerhans cell

• plays a role in the body’s immune response

• is an antigen presenting cell (APC)

• found in suprabasal location

melanocytes

• synthesize the pigment melanin and give it to keratinocytes

• amount of pigmentation is NOT dependent on the nunber of melanocytes

• star shaped