Embryology Chapter 9

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where is the oral mucosa located and what is sit composed of?

lines the oral cavity; composed of stratified squamous epithelium overlying the connective tissue proper or lamina propria.

what is located between the epithelial and lamina propria of the oral mucosa?

basement membrane

what are the three main types of oral mucosa found in the oral cavity?

lining mucosa, masticatory mucosa, and specialized mucosa

describe the location, histology, and function of the lining mucosa

buccal mucosa, labial mucosa, alveolar mucosa, mucosa lining the the floor of the mouth, ventral surface of the tongue and soft palate; nonkeratinized stratified squamous epithelium, few rete ridges and CT papillae, presence of elastic fibers to provide a moveable base; submucosa allowed for compression of the superficial tissue

Fordyce spots

granules; normal variant visible as small yellowish elevations on the surface of the mucosa;

describe the location, histology and functioning of the masticatory mucosa

noted for its rubbery surface texture and resiliency; includes attached gingiva, hard palate, and dorsal surface of the tongue; keratinized stratified squamous, pronounced rete ridges and connective tissue papillae; firm base; local anesthetic injections are more difficult and cause greater discomfort

describe the location and composition of specialized mucosa

found of the dorsal and lateral surface of the tongue in the form of the lingual papillae, which are discrete structures composed of epithelium and lamina propria

what are the three types of stratified squamous found in the oral cavity

nonkeratinized epithelium, orthokeratinized epithelium, parakeratinized epiithelium

describe the histology for each type of stratified squamous found in the oral cavity, including a description of each of the component layers.

...

what are keratinocytes

epithelial cells in the oral mucosa; produce keratin

list the other cells that are located in small number in the epithelium of the oral mucosa, what are their functions?

malanocytes, WBC, langerhans cells, Granstein cells, Merkel cells;

what are squames and where are they located?

flattened cells; show shedding or loss as they age and die during turnover;

why is the prickle layer called that?

superficial to the basal layer; named for the artifact that occurs when the epithelial cells of this layer are dried for microscopic study; cells shrink as a result of cytoplasmic fluid loss but still maintain their desmosomal cellular junctions

discuss keratohyaline granules and keratin

contained in nucleated cells; stain as dark spots; chemical precursor for the keratin found in the more superficial layers; keratin-most superficial layer; variable thickness, flat, no nuclei, cytoplasm filled with keratin
keratin- soft opaque waterproof material formed form complex of keratohyaline granules and intermediate filaments from cells

what is the difference between orthokeratinized and parakeratinized stratified squamous epithelium?

para-immature form of ortho; only normal in the oral cavity; specialized mucosa of the lingual papillae on the dorsal surface of the tongue; cells of the keratin layer - para-superficial layer, still sheds, but contains nuclei; ortho-no nuclei

what is hyperkeratinization and why does it occur?

nonkeratinized buccal mucosa when the linea alba forms; excess amount of keratin is noted on the surface of the tissue and the tissue has all the layers of an ortho tissue with its granules and keratin layers; occurs in bruxism

where is the lamina propria located in the oral mucosa and what is it composed of?

deep to the basement membrane; main fiber=collagen fiber, elastic fibers are also present; 2 layers-papillary and dense; papillary-superficial on lamina propria, loose CT in the CT papillae, blood vessels and nerve and equal amonts of fibers, cells and intercellular substances

discuss the differing types of histology as it relates to the lamina propria and the types of oral mucosa

dense layer-deep portion of the lamina propria(has CT and a lot of fibers); submucosa-may or may not be present; contains loose CT and adipose tissue or salivary glands, may overlie bone or muscle; lining mucosa-no CT papillae or rete ridges, elastic fibers present allowing speech, mastication and swallowing;

what is the most common cell in the lamina propria

fibroblast-synthesize protein fivers and intercellular substances

list the other cells found in smaller numbers in the lamina propria

WBC's, mast cells, macrophages, lymphocytes,

list the regions located in the oral cavity

labial, buccal, alveolar, floor of the mouth, ventral surface of the tongue, soft palate, attached gingiva, hard palate

describe the regional differences of the labial and buccal, both in clinical appeared and related specific histological features

opaque, pink shiny, moist, melanin, and fordyce spots, epithelium=thick nonkeratinized; lining mucosa overlies and obscures a lamina propria with vascular supply. irregular, blunt CT and elastic fibers and collagen fibers; submucosa has adipose tissue and salivary glands; firmly attached to muscle, mucosa and muscle; function as 1 unit

alveolar mucosa

reddish pink, blue vascular area, lines the vestibules of the oral cavity, lining mucosa; epithelium- thin nokeratinized, overlies but does not obscure extensive vascular supply; redder than labial and buccal; no CT, elastic fiber allows mobility

floor of the mouth, ventral surface of the tongue

reddish pink with vascular blue, moist, shiny compressible; firmly attached but allows some stretching; lining mucosa; epithelium-thin nonkeratinized; not obscuring the lamina propria. vascular supply, apparent veins. submucosa floor- loose Ct, adipose tissue, submandibular and sublingual salivary glands, loosely attached to the underlying bone and muscles; submucosa ventral- elastic fibers, minor salivary glands, extremely thin, firmly attaches to the tongue muscles

soft palate

deep pink, yellow hue, compressible, elastic; epithelium-thin nonkeratinized, thick lamina propria with numerous CT papillae and distinct elastic layers; submucosa-extremely thin with adipose tissue and salivary glands, firm attachment to the underlying muscle; lining mucosa

attached gingiva

opaque, pink, dull, firm, immobile, areas of melanin, varying amount of strippling; epithelium- thick keratinized para(some ortho); tall, narrow CT papilae, vascular supply, mucoperiosteum to the bone; no submucosa; masticatory

hard palate

pink, immobile, firm, medial portion, rugae, raphe, cushioned lateral portion; epithelium-thick ortho, medial portion rugae, raphe, mucoperiosteum to the bone; submucosa-only in lateral portions, anterior=adipose, posterior=salivary

what is stippling

little depressions which give the surface of the attached gingiva an orange-peel appearance

where is the mucogingival junction located?

sharply defined, scalloped junction between the pinker attached ginigva and redder alveolar

what is mucoperiosteum and where do you find it in the oral cavity?

when the lamina propria acts as a periosteum to the underlying jaw bonesl found on the attached gingiva to the bone

discuss the considerations for grafting in the oral cavity

performed to reduce the amount of attached gingival recession; increase the amount of attached keratinized tissue; free gingiva-palate to root; long healing time ->epithelium does not survive and it is whiter; subepithelial- attached gingiva to root; only lamina propria; more similar, less healing time

outline the anatomical features of the tongue

striated muscle in the core covered by oral mucosa, V-shaped line, sulcus terminalis ->divides the tongue into 3; ant-muscle tightly packed, no adipos; post-adipose tissue more abundant, submucosa-collection of salivary glands and muscle core; dorsal-maticatory + specialized; mast covers the surface of the muscle tissue, specialized=lingual papillae orth-para

what are the lingual papllae and where are they found in the oral cavity?

discrete structure of keratinized epithelium and lamina propria; found on the dorsal and lateral surface

list the four types of lingual papillae. which ones have taste buds?

fungiform, foliate, and circumvallate have taste buds; filiform doesn't

descrive the histology and turnover time for taste bud

barrel shaped organs derived from epithelium; 3-80 spindle shaped cells from basement to epithelial surfaces; rapid turnover-10 days

how does the process of taste take place

located on the outer portion of the taste bud; superficial taste receptors; make contact with dissolved molecules of food to produce taste sensation; food contacts taste receptors at the taste pore-opening at the most superficial portion of the taste bud; inferior portion of taste bud=sensory neuron process; nerve sends to CNS - taste is identified

describe the clinical appearance of each lingual papillae, its location and its related histological features

filiform-most common on body of the tongue, pointed cones, velvety texture; pointed structure with thick keratinized epithelium overlying a core of lamina propria; no taste buds

fungiform

less on body; mushroom shaped dots; red mushroom shaped, thin keratinized layer overlying lamina propria; taste buds on superficial portion

foliate

4-11 vertical ridges on lateral surface of posterior tongue; leaf shaped keratinized epithelium overlying a core of lamina propria; superficial taste buds

circumvallate

7-15 large raised mushroom shaped structures; anterior to the sulcus terminalis; mushroom shaped deep in the tongue surface; taste buse in base, surrounded by a trough with con ebners minor salivary gland in submucosa

where are con ebners salivary glands and what is their function?

present in the submucosa; deep to the lamina propria of circumvallate; ducts that open into the trough, flushing the area near the taste pores to introduce new taste sensation from several food molecules

explain geographic and black hair tongue and their relationship to the lingual papillae

geographic tongue-red than paler pink to white patches on the body of the tongue; change in shape; filiform papillae undergo changes from para to ortho
black-normal shedding of epithelium of filiform does not occur; thick layer of dead cells stained by tobacco, medicines, chromogenic bacteria, might be an effect of fungal overgrowth result of radiation

what can the pigmentation of the oral cavity involve in coloration?

give rise to localized flat areas of the oral mucosa that range in color from brown to brown black

what is melanin and from where is it derived?

pigment formed by melanocytes which are derived from the neural crest cells

whaere is the melanin located?

malanocytes hace small cytoplasmic granules calles melanosomes which store the melanin pigment; inject melanosomes into newly formed cells of the basal layer

compare the turnover time fo the oral mucosa and skin

skin has a longer turnover time

what are the turnover times for the most common regions in the oral cavity?

skin-27 days; hard palate-24; floor of the mouth-20; buccal/labial-14; attached gingiva-10; taste buds-10; junctional epithelium-4-6

compare the turnover time of the epithelium and lamina propria of the oral cavity

high turnover for epithelium than lamina propria; matrix-fibers and intercellular substances have rapid turnover

describe the repair process of oral mucosa

moist clot ->epithelial cells lose desmosomal junctions and form new epithelial surface under the clot -> clot breaks down; at the same time fibroblasts migrate to produce an immature CT called granulation tissue-^blood vessels, less fiber

what is granulation tissue and what complications can it cause

soft, bright red tissue that bleeds easily. may become abundant and may interfere with repair process

what is the difference between scarring of the skin and oral mucosa?

oral mucosa = less scar because fewer fibers are located in this area than skin; similar to fetal tissue repair; skin fibroblasts-mesoderm; oral mucosa-neural crest cells

what are the changed noted in the oral mucosa as it ages?

reduction of stippling on the attached gingiva, fordyce spots, enlargement of the lingual veins to form lingual viscosities on the ventral surface of the tongue, rete ridges and thickness decrease. mitotic activity ^;surface area- masticatory mucosa keratinization decreased; turnover time slows down for all tissues; collagen, elastic, and fibroblasts decreases; lamina propria=slower turnover time

whate are the clinical considerations concerning the turnover time in the oral mucosa?

delayed healing=delayed seeing the patient; higher risk because if tumor is malignant it can metastasize; radiology can damage the mucosa

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