Oral Mucosa Flashcards
mucous membrane
organ composed of 2 tissues:
epithelium overlying CT (lamina propria and SOMETIMES submucosa)
**much like skin with epidermis, dermis and hypodermis
where are blood vessels in the mucous membrane?
lamina prop/ and maybe submucosa
where are the minor salivary glands in the mucous membrane?
mainly submucosa/ sometimes lam prop
**major salivary gland ducts go through the CT, but are more removed from the oral cavity
what lymphoid tissue is in the oral mucosa?
lingual, palatine and pharyngeal tonsils
what are the functions of oral mucosa?
- barrier (epi>lam) (physical barrier)
- protection (lam>epi)
- ingestions - flexibility and moist surface for chewing and swallowing
antimicrobial capabilities of epithelial cells
beta-defensins are secreted normally but increase in number and types when invasion occurs. They are cysteine rich (+) to bind to negative charges on bacteria
**antimicrob best seen in gingiva
sensory fibers in the oral mucosa compared to the pulp and PDL
pulp (C) and dentin (A delta) and A beta and mainly only feel pain. PDL the C and Adelta fibers feel pain and Abeta is propriocep. In the oral mucosa the A beta does light touch, the Adelta and C do pain and thermal sensation and the A delta MAY do taste??
what kind of epithelium does all the oral mucosa have?
stratified squamous epi
turnover times of epithelium
- *self renewal b/c the deep layers do cells division and the superficial layers migrate, mature and get sloughed off after desmosomes break
- keratinized structures like gingiva have a slower rate than unkerat like B and L mucosa of the cheek, taste buds and junctional epi
is fast turnover good or bad?
both
can speed the healing process, but cells more vulnerable to conditions that affect cell division (ex. chemo)
make up of oral epithelium
-most of the volume is cells (keratinocytes) but also non-ketat like merkel cells, melanocytes and langerhans
merkel cells
sensory, in the basal epithelium
melanocytes
pigment, in basal epithelium - clear
*contains melanin to give oral mucosa color based on the breakdown
langerhans
(dendtritic cells) of immune system, superficial basal epi - clear
difference in layers of the kerat vs. unkerat epi
- keratinized distinct clinical appearance from unkerat
- granular in kerat and intermediate in unkerat
- keratinized layer has no organelles, dehydrated and tougher and the superficial layer has organelles and is flexible
cytokeratins
all epithelial cells (keratinocytes) have cytokeratins
-large family of genes, assembles into intermediate filaments to provide support to the cytoskeleton (2 types)
structure of intermediate filaments
type 1 (acidic) and type II (basic) - 2 major groups -cytokeratins have helical center, non-helic ends that (type I and II cytokeratins expressend in each). Coil into a heterodimer to make an intermediate filament
special property of intermediate filaments in epithelium
resist mechanical forces without breaking
**intracellular component of desmosomes and hemidesmosomes
mutations in cytokeratins
5/14 (basal layer) leads to epidermolysis bullosa
-rare, blistering in response to minor trauma, oral and non oral consequences
differences in cytokeratines
different types among layers of epi and between types and locations of epi
ex. basal layer of kerat epi has types 5/14 and spinous has K1,10
also. . K1,10 in kerat and K4,13 in non kerat
does cytokeratin expression change with disease state?
yes, 8 and 18 are in junc epi normally but in other epi layers during disease
white sponge nevus
- autosomal dominant disorder (rare), mutations in cytokeratins 4 and 13, especially helical region, affects oral, non-kerat epi
- *white spots on B mucosa (regionally specific)
- *swollen or missing cells histologically
functional diff in kerat vs. nonkerat
kerat is tougher and nonkerat is more flexaible due to the cytokeratins present (both increase as you travel more superficial)
**kerat is also more impermeable because desmosomes more numerous
biochemical prop of kerat
-aggregation of individual fibers into tonofibrils to make tough, and filagrin (of kerohyalin granules) starts to bind to tonofibrils so that by the keratinized layer there are a ton of tonofibril/filagrin complexes with no organelles, dehydrated and flat
biochem prop of nonkerat
-cytokeratin types in nonkerat do not promote aggregation (no complex with filagrin) and superficial layers are not as dehydrated and retain nucleus “cytokeratin tonofilaments”
membrane coating granules
- in upper prickly layer of nonkerat and kerat, membrane bound organelles filled with glycolipids. released to more superficial layers (like was going intercellular spaces)
- *serves as a barrier to aqueous substances but chemical comp is unkerat and kerat lead to a more effective barrier in kerat epi
membrane thickening
more pronounced in kerat
- cornified envelope (15 mm) of cross linked protein sheath of loricrin and other proteins that keep substances going btwn cells
- *inner face btwn keratinocytes
parakeratinized
have keratohylane granules but retain nucleus
incomplete keratin
fluid-filled layer
hyperkerat
areas subject to irritation (ex. msokers)
lamina propria composition
- most volume occupied by ECM
- have fibroblasts, macrophages, mast cells and inflamm cells
- ECM is pgs and gags, glycopro (connect), collagen type I and III and elastin
collagen in the lam prop oral muc
-different for different areas. More type 1 for harder CT like gingiva and more type III for softer CT like buccal mucosa
why is elastin needed in oral mucosa
to accomodate moth movements (more prom in pulp or PDL)
epi/CT interface
(basal lamina)
-2 layers of lam prop: reticular (deep) and papillary layer (superfic) that protrude up into epi layer) and rete pegs of the epi that protrude down into the CT
gingiva stippling
underlying rete pegs and CT papillae (CT protruding into epi)
submucosa
-present in some regions, contains larger blood vessels and nerves to supply the superfi LP, contains salivary glands, separates LP from bone and muscle
if no submucosa
LP directly to bone or mm.
ex. tongue, gingiva, hard palate, ruage and median raphe
LP to bone?
mucoperiosteum
masticatory mucosa
gingiva and hard palate
- kerat, dense LP (more collagen than elastic), many long, thin CT papilla), submucosa is variably present
- *incisions dont gape and injections more painful
lining mucosa
everything else (not ging or hard palate)
nonkerat (parakerat)
-fewer collagen and more eleastic in LP
-short broad CT papilla
-submucosa present
-attachment to bone/mm flexible
**injections less painful and cuts more likely to gape
specialized mucosa
vermillion borders and tongue
explain the lip region
exterior sin is keratinized and thin, sweat glands and hair follicles, the vermill zone is keratinized, thin, blood vessels close to surface and no glands the labial mucosa is non-kerat, thick and has mucous glands
sulcular epi
-part of free gingiva that faces tooth, non-kerat
junctional epi
- unique, forms seal with hard tissue (enamel and cementum), oriented along long axis tooth, thicker at top than bottom, STRAIGHT BASEMENT MEMBRANE, keratin expression (simple epithelium), non-differentiated cells really, HIGHLY PERMEABLE (bad for bacteria to get down) **SENSITIVE,
- *more tonofibirls than desmosomes and no membrane coated granules
junctional epi basal lamina
there are 2 (external and internal) the external is btwn the JE and lam prop and an internal btwn the JE and tooth
**internal has integrins and a unique type of laminin but lacks type IV and VII collagen
why no type Iv and VII collagen in internal basal lamina?
integrins bind to laminin to make the cross linked type IV collagen that are a direct link to the soft CT of lam prop but because the internal basal lam is conecting to hard tissue, different structure
what protein is in JE?
ODAM (ODONTOGENEIC AMELOBLAST-ASSOCIATED PROTEIN)
from the REE that is associated with ameloblasts
can JE regenerate?
yes, relativelt fast and around dental implants
vascular supply of gingiva
maxilla (superior alveolar a. and palatine) and mandible (inf. alveolar a., buccal, mental and sublingual a.) go to the PDL, interdental septa and oral mucosa to then feed into the gingiva (eventually leak out the periphery)
