Oral histology (cilnical oral histo & Emrbyo)

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The first structure in the formation of tooth?

enamel organ

enamel organ for deciduous teeth appear when?

a. 6-8 week old embryo
b. 4 months in utero
c. 10 month old child

a. 6-8 week old embryo (correct)
b. 4 months in utero
c. 10 month old child

the first time enamel organ for permenant teeth appear at what time?

for 1st molar: 4th month in utero - 10 month old child

3rd molar - 5 yrs old child

What embryonic structure divides the <b>mandibular prominence</b> into lip and future alveolar process.

Labial-vestibular lamina

this structure forms a wedge that then breaks down to form the vestibule with only a thin epithelial lining.

What structure burrows into the connective tissue from the lingual aspect of the vestibular lamina?

Dental lamina (arm of epithelial tissue)

There are initially 10 of these arms forming the future 10 deciduous teeth.

The first stage of enamel organ is:

formation of tooth bud by clumping of the the CT cells (Neural crest cells) around the developing dental lamina.

Which stage is formed first?

a. cap stage
b. bell stage

a. cap sate

Cap stage is when the very end of the dental lamina flattens out to form a structure resembling a small flat hat. This formation quickly changes to appear as a bell.

During bell stage, the bell like structure is surrounded by the neural crest cells which are now given the name ________ which will become PDL later.

'Follicle' or 'sac'

The inner enamel epithelium (IEE) is a layer of cuboidal cells that forms the inside rim and whose shape determines what structure?

future DEJ

The group of cells fills the space between the IEE and OEE and act as a bubble wrap protecting the DEJ.

Stellate reticulum

Function of Stratum intermedium?

to pass on metabolites to the future ameloblasts.

What embryonic structure determines the shape of the root of the tooth.

Cervical loop

Once the enamel and dentin are laid down, how does the nutrition gets to IEE and stratum intermedium?

through diffusion of IEE and OEE at a point so the nutritients can be obtained from external vessels.

(T/F) many cysts and tumors arise from the enamel organ.

True

Amelogenesis and odontogensis processes start at what stage?

<b>late</b> bell stage

(T/F) the change to preameloblast occurs before the formation of preodontoblast but odontoblast produces dentin before ameloblast produces enamel.

True

Stages of Amelogenesis (4)

1. Morphogenic- inner enamel epithelium
2. Differentiation- polarization of the nuclei
3. Secretory- synthesis of enamel
4. maturation- reduced ameloblast, add'l calcium to 96%

two main proteins involved in amelogenesis:

1. Amelogenin (90% of matrix)
2. Enamelin (10%) - slightly hypomineralized at DEJ and assocaited with <b>enamel tufts</b>

Which enamel protein is associated with Enamel tufts?

Enamelin

mantel dentin is formed using proteins from:

When dentin matrix is first laid down, the odontoblasts use the protein molecules made by nearby connective tissue cells.

ONLY after the initial 150 micron, odontoblasts is able to lay down its own matrix! (T/F)

True

The dentin is divided into mantel dentin and _____.

circumpulpar

The fact that an ameloblast can produce an enamel rod independent of its neighbors depends on which type of junction?

Occluding or tight junction

Connexon

A channel formed in a gap junction by the attachment of six connexin proteins on one cell to six <b>connexin</b> proteins on another

What percentage of the cellular energy is spent on Na/K pump?

1/3

Is Na+ pumped out during phosphorylation or dephosphyrlation of the carrier protein?

phosphorylation

K is brought in during dephosphorylation

Attachment plaques consists of dense material of proteins called _________ and _________.

Desmoplakin
Plakoglobin

A single ameloblast produces a single rod exuded from ________.

Tome's process

What's the importance of distal terminal web?

to preserve the rod as it is formed by sealing the sides of the ameloblast and preventing any leakage of matrix.

main transmembrane protein in DTW?

Claudin

Laminin belongs to ________ family.

Integrin

The collagen IV of basal lamina is formed by:

a. fibroblasts
b. eipthelia
c. neither

b. epithelia

What protein connects the basal lamina to enamel or implant?

Syndecan, a glycoprotein transmembrane molecule.

it also attaches to Type I and III

is a group of <u>glycoproteins</u> found on cell surface and on connective tissue that promote cellular adhesion and migration.

Fibronectin

Perlecan

(a complex carbohydrate) binds to fibronectin to <u>enhance</u> the latter's <u>stikyness</u>

What collagen type(s) make(s) up the principal fibers?

Types I and III

______________ extends from <b>basal lamina</b> to the <B>elastic fibers</b> in the CT matrix.

Fibrillin microfibers

Amelogenesis imperfecta is caused by autoimmune reaction to __________.

claudins

Pemphigus is caused by deficiency of ________.

cadherins

Bullous pemphigoid

Bullous separates at Basement membrane

antibodies to bullous pemphigoid antigen on basement membrane
acquired

Stable blisters because of normal epithelium (all underneath)

the cause is due to deficiency of transmembrane proteins such as <b>Type XVII collage, laminin, transmembrane integrin</b>.

A mutation in fibrillin microfibers leads to which disorder?

Marfan's syndrome

__________- layer develops keratohyaline granules.

Stratum granulosum

When keratohyaline granules from stratum granulosum have matured to keratin, they form:

Stratum corneum

these are dendritic cells found in the oral mucosa which produce melanin.

melanocytes

(T/F) the term mucosa means epithelium + Lamina propria

True

the floor of the mouth is an example of:

a. submucosa
b. mucoperiosteum
c. Fibrous submucosa

a. Submucosa (floor of the mouth)
b. Mucoperiostium (attached gingiva)
c. fibrous submucosa (palate)

This term descibes abnormal thickness of the stratum corneum.

hyperkeratosis

This term describes abnormal thickness of the prickle cell layer.

Acanthosis

This term describes abnormal mitosis along with hyperchromatism and atypical nuclei in all the layers.

dysplasia

(T/F) intermediate fibers increase in number as the cells approach the surface, esp stratum corneum.

True

glycocalyx

external surface of the plasma membrane with carbohydrates attached to it. they are present in Prickle cell of the lining mucosa.

Elastic fibers are more prominent in MM or LM?

LM

Submucosa layer of MM

non existent (attached directly to underlying bone, mucoperiostium) or a fibrous submucosa that is filled with fat cells (anterior palate) and minor mucous salivary glands (posterior palate) that makes submucosa very rigid yet still able to cushion a load to protect underlyng blood vessels and nevers

Loss of stippling of the attached gingiva along with loss of the free gingival groove is caused by:

edema of the lamina propria and is an early sign of gingivits.

Reduced ameloblast is:

a. cuboidal
b. columnar

a. cuboidal

? -----> reduced ameloblast

ameloblast

2 important functions of reduced enamel epithelium (REE)?

1. protection of enamel
2. forming the initial steps in connecting the oral mucosa to the tooth.

Inner basal lamina

the part of the reduced enamel epithelium which is attached to the enamel by hemidesmosome.

The part that is attached to the surrounding CT by hemidesomoem is called OUTER basal lamina.

(T/F) Junctional Epithelium extends from the CEJ to the part where epithelial tissue is not longer attached to enamel.

True

Which two layers disappear in masticatory mucosa?

1. Stratum corneum
2. stratum granulosum

Reduced enamel epithelium (REE) is attached only at the cervix (T/F)

True

focal adhesion

this is the way fibroblasts and other neural crest driven cells migrate from point to point.

__________ fastens the fibroblast to extracellular collagen matrix using a transmembrane macromolecule.

Fibronexous

A sticky glycoprotein on the collagen fiber's surface produced by the fibroblast

Fibronectin

Perlecan

makes the fibrinonectin more sticky

Syndecan

The transmembrane macromolecule, attaches one end of itself to the sticky combination of <b>fibronectin and perlecan</b> on the collagen fiber while the other end of syndecan along with laminin, connects to the <b>fibroblasts cell's cytoskeleton of intermediate fibers.</b>

Syndecan also connects the underside of the TYPE IV mat to fibroblasts, connective tissue and prosthesis.

Tenasin is secreted by:

fibroblast

(T/F) tooth eruption is due to contraction and relaxation of __________.

Fibroblasts which are attached to collagen which is attached to the tooth <u>cementum</u> by sharpeys fibers.

4th germ layer

neural crests (ectomesenchyme: part connective tissue cells, part epithelial cells)

Ectomesenchyme

a type of mesenchyme from the ectoderm, which is influenced by neural crest cells that have migrated to the area.

(T/F) the CT that supports the epithelium determines the type of epithelium.

True

ex. masticatory and lining epithelium.

As soon as enamel matrix has formed, the cervcial area of the enamel organ forms a sheath of cells, ___________, that will outline the shape of the root to come.

Hertwig's sheat

What structure separates CT cells that lie on the future pulpal area from those that lie on follicle.

Epithelial diaphragm (ED)

<b>Fibroblasts</b> that are next to the outer surface of Hertwig's sheath become ________.

PDL

What portion of the anterior teeth roots are covered with Acellular cementum

all of it

2/3 of the posterior teeth

What type of collagen fibers are found in the ACellular cementum matrix?

II and IV

type one in cellular cementum

What type of collagen fibers are found in the PDL?

I and III

Eruption speed

1 mm every 3 months

How does body compensates for occlusal wear?

with deposit of apical cementum

The radicular cysts which are located at the apex are driven from what type of cells?

epithelial cells, to be more specific. from the epithelial cells of the Debris of Malassez that are near the apex of the infected pulp.

The __________ is the transition area between epiphysis and diaphysis.

metaphysis

The first appearance of interredicular dentin appears where?

on the tab of epithelial diaphragm.

Secretion from which cell is mostly composed of protein with some polysaccharide?

a. serous
b. mucous

serous

Therefore you would expect to see a lot of rough ER.

Exocytosis is the process by which __________ cells secrete their products.

a. serous
b. mucous

a. sereous

mucous cells are by rupturing

__________ cells are found around the cell wall of mucous and serous cells and have a contractile ability to squeeze out fluid.

myo-epithelial cells

MC= myoepithelial cells
SC= Serous cell
SEE= Serous secretory end piece

eosinophilic cells, especially in aged, has no known function but tumors can develop.

oncocytes

they are bright red cells that arise from <b>striated ducts</b>.

fat cells replace much of the parenchyma of what glands? What is the consequence of this?

serous glands

Saliva becomes stringy -> loss of the buffering capability of the saliva.

Saliva can pass out of the cell not only at the apex of the cell, the usual exit, but through opening in the sides of the cell into tiny canals called ___________ that lie between cells that also lead into the intercalated ducts.

intercellular canaliculae

What are the three different arrangement of the salivary gland cells?

1. Spherical acinus in <b>serous glands</b>
2. Tubular acinus in <b>mucus glands</b>
3. Tubula acinus (mucous) AND Demilunes of Gianuzii (serous) in mixed acini.

Parotid gland

watery fluid rich in amylase (<b>spherical endpeice</b>)
-- Oncocytes and fat cells take over as age increases

Submandibular gland

mixed gland but mostly serous <b>spherical endpeice</b> plus few demilunes on top of mucous cells.

What two salivary glands have capsules?

parotid and submandibular THUS post-parandial pain is <b>pathognomic</b> symptom of stone blocking the duct at meal times becomes of back pressure of the blocked saliva.

__________ is a mixed gland but mostly mucous.

Sublingual...VERY viscous
-tubular end piece
- many demilunes of Gianuzzi
- No capsule ---> permits early infiltration of malignant tumors.

Most minor salivary glands are _______.

mucous glands

What are the the only two places in the oral cavity where you would not find minro salivary glands?

1. gingiva
2. anterior palate

What are the two MAIN secretory ducts in the oral cavity

1. Inter-cellular canaliculi
2. Apex of parenchymal cells: serous exocytosis...mucous: cell wall rupture
3. Intercalated ducts
4. Striated ducts

5. Psuedostratified ciliated epithelium
6. Stratified squamous: Stenson's and Wharton's ducts

Stenson's duct

parotid duct; route saliva takes from parotid gland into mouth

Wharton's duct

submandibular duct (salivary duct) ~5cm long; much thinner wall than Stenson's duct

Which salivary gland has higher chance of developing malignant tumor formation?

Sublingual (no capsule)

Pain after eating is known as:

Post-prandial pain

What is symtpom that is ONLY assocaited with post-prandial pain?

Patho-gno-monic

striated duct

remove Na+ and adds K+ HCO3- in saliva

Mucous cells

demilunes of Gianuzzi are found in abundant in which gland??

sublingual gland

Two structures that prevent <b>lines of cleavage</b> in enamel.

1. Gnarled enamle
2. enamel tufts

__________produces enamel.

Ameloblast

(T/f) Enamel is formed from ectoderm but dentin is formed from mesoderm.

Treu

the matrix for dentin is deposited by odontoblasts at what rate?

4 micron daily increments.

The extentuated lines of von ebner is called:

lines of owen

What structure(s) give dentin its proper elasticity?

primary and secondary curvature

A fully calcified dentinal tubule is called:

dead tract

change in existing tissue is called:

protective metamorphesis

the dentin that is deposited in response to abrasion caused by tooth brush is:

reparative secondary dentin

We have pulp chamber which is coronal and ___________ which is root canal.

radicular area

most distinctive cells of the pulp.

odontoblasts

cells in the greatest numbers in the pulp

fibroblasts

What type of collagen is found in the matrix of the pulp?

I and III

others: ground substance (protoglycans and glycoproteins)

What do you find in a young pulp?

lots of fibroblasts with LARGE nuclei and not much collagen.

What causes narrowing of the pulp chamber by age?

deposition of secondary dentin

cementum is ___% calcified

50%

What structure forms the root formation

Hertwig rooth sheath

The tip of the Hertwig sheath is called

cervical loop

___________ eventually forms the epical foramen.

epical diaphragm

Opposite of adult laminar bone is

Immature woven or juvenile bone.

______________ separates stomodeum from GI tract

Buccopharyngeal membrane

It BREAKS DOWN at the END of 4th week.

What two embryonic processes make up the <b>first branchial arch</b>?

Maxillary process + Mandibular process

What structure makes up the <u>second</u> branchial arch?

hyaloid arch

What emrbyonic structure provides the communication between the <b>eye</b> and the <b>nose</b>?

Nasolacrimal Groove

location: lies between the maxillary process (MAX) and Lateral nasal process (LNP)

extends from Inner canthus of the eye to the nose.

5 weeks embryo

Nasal lacrimal groove first appears when?

in 6 weeks embryo

Nasal pit first appears in:

5 weeks embryo

What two structures form the root of the tongue?

2nd and 3rd branchial arch + copula

What structure(s) form the BODY of the tongue?

1. 3rd branchial arch
2. lateral tubercules
3. Tuberculum impar

Fusion of medial nasal process (MNP) and maxillary process takes place in what week?

7th week

If it doesn't happen ----> CLEFT LIP!

Fussion of Medio nasal process with frontal nasal process?

7th week

they form ----> primary palate!!

Future Columella appears in what week?

7th week

In this week, the Lateral tubercules come together pushing the tuberculum impar out of sight.

Week 7

What structure prevents the <b>palatine processes</b> to come together?

the tongue (T)

MC- Meckel's cartilage
MB- Mandibular bone

Tongue finally drops down in ________ week.

9th week

Downgrowth of palatine shelves occur in 9 weeks. (T/F)

True

palatal plates come together to from the <b>hard</b> palate.

Fuse with the <B>median palatal triangle</b> also occurs in 9 weeks

Fusion of palatal shelves with primary palate occurs in what week?

week 9

What happens if the primary palate does NOT fuse properly with primary palate?

Cleft palate (9 weeks)

What are the three anatomical segments of primary palate?

Prolabium
Premaxilla
Median palatal triangle

primary palate is formed from <i>2 medial nasal processes and fronto-nasal processes (MNP and FNP)

The dental lamina and vestibule lamina are formed in what weeks?

5-6 week

Three stages of tooth development:

1. Bud
2. Cap
3. Bell

Star shaped cells, preserve shape, integrity of the future DEJ.

Stellate reticulum

Bell stage starts at _____ weeks

14

Reduced Enamel epithelium eventually becomes _______.

junctional epithelium

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