| Contributed by:
Andrea and Cristal
SDH PRCC, MS
Histology Study Sheets
5
processes in the embryo:
1.
Induction: interaction between cells, cells talking to each other.
2.
Proliferation: controlled levels of cellular growth with accumulation of
cellular by products.
3.
Differentiation: change that occurs in embryonic cells that is identical
genetically so they can become structurally & functionally different. Any cells
formed during this time are those, which perform a specific function such as,
heart, lungs, liver, kidney. They form at different rates.
4.
Morphogenesis: development of specific tissue by their form by migration
of embryonic cells. Continued interaction among cells to develop into different
forms.
5.
Maturation: fetal period (adult size & form).
2 layers of
the bilaminar disc:
|
Top layer: epiblast layer: columnar cell shape: AKA ectoderm. |
|
Bottom layer: hypoblast layer: small cube shaped cells: AKA endoderm. |
Layers of
the trilaminar disc:
|
1st layer: Ectoderm: create epidermis of skin, nervous
system, tooth enamel, epithelium of eye, ear, nose, sinuses, oral &
nasal cavities, hair & nails. |
|
2nd layer: Mesoderm: create muscle, PDL, blood, dentin,
pulp, cementum. |
|
3rd layer: Endoderm: creates lining of GI tract &
respiratory processes. |
5 Facial
processes:
|
Stomodeum |
becomes primitive mouth.
Before the 4th week can start
seeing it as a shallow depression.
Not very deep due to temporary membrane that
is present.
Temporary membrane= Oropharnygeal membrane
that will disappear when face starts to develop & mouth will be larger. |
|
Maxillary Process |
grow on either side of primitive mouth &
eventually form mid face.
cheeks, corners of mouth, palate, maxilla,
zygomatic & temporal bone, sides of upper lip. |
|
Mandibular arch |
1st to form after primitive mouth.
forms lower face. |
|
Frontonasal Process |
form upper part of face.
forehead, bridge of nose, palate, nasal
septum. |
|
Nose |
forms during 4th week.
tissue on either side (placodes) develop into
nose.
|
Brachial Arches
|
1 |
Mandibular arches |
Innervated by CN V |
Meckle’s Cartilage |
Form middle & lower face |
|
2 |
Hyoid arch
|
Innervated by CN VII |
Reichert’s Cartilage |
Form hyoid bone, facial muscles, tongue, and middle ear bone. |
|
3 |
Unnamed arch
|
Innervated by CN IX |
Unnamed cartilage |
Forms pharyngeal muscle & portion of hyoid bone. |
|
4-6 |
Unnamed arch
|
Innervated by CN IX & CN X |
Unnamed cartilage |
Form muscles of larynx & pharynx. |
|
5 |
This arch is so primitive it is usually absent in humans. |
NONE
|
NONE
|
NONE
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Stages of Tooth Development
|
Initiation
Stage |
6-7 week of
development.
induction/interaction between cells.
Primative mouth
lined with ectoderm & leads to formation of oral epithelium & below that
layer is a layer of mesenchyme.
Oral epithelium
layer will continue to grow & form dental lamina. |
|
Bud Stage |
8th
week of development.
Dental Lamina
grows/ evolves into a bud. |
|
Cap Stage |
9th-10th
week of development.
Bud turns
concave & forms a cap.
Proliferation/
differentiation: tooth bud is becoming structurally & functionally
different.
Morphogenesis:
takes on specific tissue characteristics. Occurs in unequal growth
patterns. |
|
Bell Stage |
11th-12th
week of development.
Proliferation,
differentiation, morphogenesis.
Enamel organ
differentiates into 4 layers. |
|
Apposition/
Maturation |
Varies per
tooth.
Induction,
proliferation,Maturation.
Final stage is
amelogenesis. |
The enamel organ differentiates into these
layers in the
Bell Stage
|
1st |
Outer enamel epithelium
|
Cube shaped cells
|
Protective barrier to enamel organ. |
|
2nd |
Inner enamel epithelium
|
Tall columnar cells
|
Form outline of future shape of tooth crown & eventually become
ameloblasts. |
|
3rd |
Stellate recticulum
|
Cells are star shaped
|
Help support production of enamel. |
|
4th |
Stratum intermedium
|
Flat cells
|
Support production of enamel. |
Organelles of the cell with
their function:
|
Nucleus |
DNA/RNA inside help control functions of cell. DNA=genetic code, RNA=
control cellular protein synthesis.
located near center of cell.
largest organelle. Brain of the cell. |
|
Mitochondria |
power plant of cell
second largest
generates energy by making ATP. |
|
Ribosomes |
also
protein factories for cell.
can
be free or bound to membrane, can be single or in clusters within cell. |
|
Endoplasmic recticulum |
store & transport proteins.
smooth: no ribosomes; synthesize lipids/carbs. Rough: has ribosomes;
synthesize protein. |
|
Golgi Complex |
transports proteins & produce lysosomes. |
|
Lysosomes |
called little digestive bags because enzymes will digest materials taken
into cell.
produced by golgi. |
|
cytoskeleton |
between liquid & gel.
provides skeletal support to cell. |
Phases of cell division:
|
Prophase |
Nuclear membrane will disappear. |
|
Metaphase |
Chromosomes line up down middle of cell & spindle forms. |
|
Anaphase |
2 daughter chromosomes migrate to opposite poles. |
|
Telophase |
Cytokenesis occurs: division of cytoplasm, nuclear membrane reappears. |
|
Interphase |
Cell at rest between divisions, grow, metabolize. Organelle replacement
& produce substances for division. |
Layers of Basement Membrane
Epithelium
|
|
Basal Lamina: made
from epithelium: has 2 layers: |
|
Lamina Lucida: (clear) close to epithelial layer. |
|
Lamina Densa: (denser) found close to connective
tissue layer. |
|
Reticular Lamina:
collagen fibers produced by connective tissue. |
Connective tissue
|
lips/cheeks, floor of mouth, underside tongue, soft palate, alveolar
mucosa.
non
keratinized.
not
firmly attached to underlying bone.
can
be stretched or compressed.
Fordyce’s granules 80% adults-sebum |
Lining mucosa |
gingiva & hard palate. keratinized.
firmly attached to underlying bone. chewing.
|
Masticatory mucosa |
dorsum & lateral of tongue.
keratinized.
|
Specialized mucosa |
Filiform
papilla: most numerous, no taste buds. Fx: aid food to guide in swallowing.
Fungiform papilla: have taste buds, red mushrooms.
Foliate
papilla: have taste buds, lateral borders of tongue.
Circumvale papilla: have taste buds, 10-14 v shaped on back of tongue.
Most common
type of epithelium in the oral cavity: non-keratinized epithelium.
3 layers of
non-keratinized epithelium:
a.
Basal layer~ mitosis occurs.
b.
Intermediate layer~ makes up the bulk of non-keratinized epithelium.
Superficial layer~ so much like
intermediate can’t tell the difference
Least common
type of epithelium in the oral cavity: orthokeratinized.
4 layers of
orthokeratinized epithelium:
a.
Basal layer: mitosis occurs.
b.
Prickle cell layer: makes up the bulk of orthokeratinized.
c.
Granular Layer: contains keratohyaline granules- substance in the form of
granules that are found in cytoplasm of cells.
d.
Keratin layer- keratin, varying degrees of thickness, cells are flat with
no nuclei.
The
parakeratinized epithelium has the same layers as orthokeratinized, but the
keratin layer is different in that: its cells have nucleus.
Discuss the histological
differences in:
a. Labial/buccal mucosa: pink,
thick, non-keratinized.
b. Alveolar mucosa:
non-keratinized, thin, red.
c. Floor of mouth & ventral tongue
surface: non-keratinized, pink/red, thin.
d. Soft palate: deep pink,
non-keratinized, thin.
e. Attached gingiva:
parakeratinized (has some keratinization), pink, stippling.
f. Hard palate:
orthokeratinized, thin…. why injections hurt.
Renewal Rates:
junctional epithelium
|
4-6 days |
taste buds
|
10 days |
buccal / labial
|
10-14 days |
attached gingiva
|
10 days |
List the types of gingival
tissues:
- Free gingiva- encircles the
tooth.
- Attached Gingiva- connected
to tooth.
- Interdental gingiva-
between teeth.
3 types of
salivary glands:
Parotid gland
Encapsulated |
Largest
salivary gland |
25% of
total saliva volume |
Serous &
mucous |
Stensons
duct |
|
Submandibular gland |
2nd
largest |
60-65% of
saliva volume |
Serous &
mucous |
Whartons
Duct (opens sublingual carnucle) |
|
Sublingual gland |
smallest |
10% of
saliva volume |
Mucous &
serous |
Sublingual duct/Bartholin Duct (opens under tongue, gleeker gland) |
Enamel:
Hardest
calcified tissue in the body.
No nerves or
blood supply.
96%
inorganic material: hydroxyapatite.
3% H2O
1% organic
material: calcium phosphate/ phosphorus.
Dentin:
70%
calcium hydroxyapatite (inorganic)
20%
organic
10%
water.
Cementum is
made up of:
65% calcium
hydroxyapatite
23% organic
12 % water.
Disclaimer: These notes were
copied and pasted from files sent to me by Andrea. They have not been reviewed for errors. You are
responsible for checking out the information to verify the accuracy. This site,
Amy Nieves
and Andrea are not responsible for typographical errors.
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