Tooth Development & Structure Flashcards
Formation of a ball of cells, called the
Mourula
Fluid accumulates In the morula; its cells realign themselves
Formation of a fluid-filled hollow ball, called the
blastocyst
The cells on the outer later of a blastocyst are called?
Trophoblasts
The cells on the inner layer of a blastocyst are called?
Embryoblasts
The human mourla developes rapidly within days following ?
Fertilization
On day 5 of development, the human blastocyst contains what?
- Zona pelucida
- Trophoblast
- Blastoceal (yolk salk)
- Embryoblast
What is another word for the yolk sack?
Blastocoel
Coel=hole
What an egg is fertilized how long does it take to become a mourla? then a Blastocyst?
Moural= day 3/4
Blastocyst= 5/6
At day 8 after fertilization, the inner cell mass ____ differentiates into 2 groups of cells.
Embryoblast
What are the 2 groups of cells which the embryoblast layer differentites into?
- Epiblast
- Hypoblast
At the stage in which the embryoblast differentiates into the epiblast and hypoblast layer this is a a ____
Bilaminar embryonic disk
2 layer embryonic disk
In Bilaminar Germ Disk
are columnar and reorganize to form the amniotic cavity
Epiblasts Cells
The epiblast cells will reorganized itself to form the ____ and ____ linnig the amniotic cavity
- Forms embryo
- Forms epithelilial layering lining the amniotic cavity
The epiblast layer will form the entire embryo and undergoes gastrulation in week three to form the what?
3 germ layers
In Bilaminar Germ Disk
are cuboidal and form the roof of the secondary yolk sac
Hypoblast cells
In week three, the hypoblast layer is replaced by the gastrulation migrating
Endoderm cells
The hypoblast layer is considered a
A primitive “endoderm”
Not true; only precourssor
The epiblast layer is considered a what?
Primative ectoderm
Not true; only precoursor
Summary
Summary
Formation of the true germ layers
is the beginning of morphogenesis (development of body form) and is the significant event occurring during the third week.
Gastrulation
During gastrulation, the bilaminar embryonic disk is converted into a ?
trilaminar embryonic disk
development of body form
Occurs during gastrulation
morphogenesis
During gastrulation, ____ is established in the embryos
axial orientation
Develop head and tail orientation
refers to the anterior (front) aspect of the embryo
Ventral
refers to the posterior (back)
Dorsal
relating to the head
Cephalic
Relating to the tail or back of head
Caudal
is a transient embryonic anatomy structure required for patterning the surrounding tissues.
Notochord
Neuroembryological terms
are only used to describe structures within the central nervous system, above the level of the spinal cord (e.g., brainstem, cerebrum and cerebellum).
Roastral and Caudal
refers to the anterior (front) aspect of the head.
Rostaral
dorsal refer to the anterior and posterior aspects of the body, respectively.
Ventral (front), Dorsal (back)
In the brain, ventral refers to what?
inferior region of the brain
In the brain, dorsal refers to what?
refers to the superior region (towards the scalp).
Cells of the epiblast divide and migrate toward the
The primative streak
Cells of the epiblast divide and migrate toward the primitive streak.
displace and replace the hypoblast cells and become the what?
True embryonic endoderm
Cells of the epiblast divide and migrate toward the primitive streak.
they can also pack themseleves between the newly formed embryonic endoderm and epiblast to form the ?
Mesoderm
the remaining cells of the epiblast are the?
Ectoderm
Gastrulation views
Gastrulation Views
Following the for mation of the triboblastic embryo, for the next 3-4 weeks what develops?
Major tissue development
include the head, face, and tissues contributing to development of the teeth.
What layer of cells do teeth develop from?
Ectoderm
Issues of the skin, hair, pigment, neurological issue are clinical manifestions of what?
Issues with emrbyological developmen of the ectoderm
What layer?
- Skin cells of epidermis
- Teeth
- Nueron of brain
- Pigment cells
Ectoderm
External layer
What layer?
- Cardiac muscle
- Skeletal muscle cells
- Tubule cell of the kidney
- RBC
- Smooth muscle in gut
Mesoderm
middle layer
What layer?
- Lung cells
- Thyroid cells
- Pancreatic cells
Gut
Endoderm
interior layer
3 key events
What are 3 key events of the formation of the neural tube and fate of germ layers?
- Differentiation of nervous systema nd neural crest tissue from ectoderm
- Diferentiation of mesoderm
- Folding of embryo in 2 planes (rostral-caudal) & (lateraly)
At weeks 6-8 of embryonic development, the ____ is formed from ectoderm.
neuroectoderm
Eventually froms the brain
A group of cells separate from the neuroectoderm. These are
Neural Crest Cells
Embryonic connective tissue elsewhere is derived from mesoderm and is known as
Mesenchyme
**Embryonic connective tissue **in the head is derived from mesoderm and is known as
ectomesenchyme
“Periodontum (connective tissue) is ectomesychimally derived”
Produced from the fusion of the neural fold beneath the surface of the ectoderm
Neural tube
Anteriorly, the neural tube expands to form what 3 things?
- Forebrain
- Midbrain
- Hindbrain
develops a series of 8 bulges (the rhombomeres)
Hindbrain
The posterior neural tube developes into the?
Spinal cord
A series of externally visible tissue bands
Give rise to the structures of the head and neck
Pharyngeal Arches
Cranial neural crest-derived mesenchymal cells (ectomesenchyme) migrate into pharyngeal arches from midbrain and hindbrain region forming what 6 kinds of cells?
- Neurons
- Schwann cells
- Smooth muscle cells
- Osteoblasts
- Chondrocytes
- Odontoblast
Cells that form teeth
Odontoblasts
Abnormalities in the head and face are a result of issue with ___ ___ cells in head and neck formation during embryological formation
neural crest cells issue
The underdevelopment results from a Failure of the neural crest cells to migrate to the facial region.
* Drooping eyes
* Bad hair
* bad teeth
* Bad skin
* neurological defects
Treacher Collins syndrome
able to develop into the tissues of the lymphatic and circulatory systems, as well as connective tissues throughout the body, such as bone and cartilage.
Mesenchyme
Most of the time, mesenchyme is derived from the ____ but, in certain exceptional cases, the mesenchyme may be derived from the ____ (from neural crest cells) [ectomesenchyme].
Mesoderm derived = mesenchyme
Ectoderm derived from neural crest cells= ectomesencym
Neural crest cells eventually from what in moutth?
Connective tissue!
* PDL
* Alevolar bone
* Dentin
etc
surface ectodern
Enamel Formation
AMELOGENESIS
Cells: ameloblasts
Ectodermal origin
Amelogenisis
What cells help in enamel fromation?
Amenoblasts
Dentin-Pulp complex formation
Dentinogenisis
Cells: odontoblasts
Ectomesenchymal origin
Dentinogenisis
What cells aid in dental pulp complex formation?
Odontoblasts
Cementum formation
SUPPORT TISSUES FORMATION
Cells: cementoblasts
Ectomesenchymal origin
Support tissue formation (cementum)
What cells aid in cemenetum formation?
cementoblasts
What are the 3 overlapping phases of tooth development?
- Inititation (est. site of future teeth)
- Morphogenisis (det shape of tooth)
- Histogenisis (fully formed dental tissue via cell differentiation)
What stage of tooth dev?
Establish sites of future teeth.
Initiation
What stage of tooth dev?
Determine shape of tooth.
Morphogenisis
What stage of tooth dev?
Fully formed dental tissues via cell differentiation.
Amenoblast, cementoblast, odontoblast start to develop
Histogenisis
During inital embryological development there are designated areas for both __ and ___.
Primary and permanent teeth.
All teeth are pre-formed. (primary 1st, secondary later)
why mothers health during pregnancy affects in child
What are the 3 stages of tooth formation?
- Bud
- Cap
- Bell
Inward growth onto the underlying ectomesenchyme the on each thickened epithelial shelves
Signals beggining of tooth development
Dental Lamina
S
The ____ thickens into dental lamina, and ectomesencyme cells migrate around it
Primary epithelial band
Outer epithelium thickens to from dental lamina.
Explain A and B
Dental lamina (B)- lingually located
Vestibular lamina (A)- buccally located
thickening of dental OE itno dental lamina singals tooth development initiation
are embryonic structures that give rise to structures such as hair follicles and teeth
form along dental lamina, signal where bud will form
Dental Placode
Condensation!
first epithelial incursion into the ectomesenchyme of the jaw.
Cells show little change in shape or function.
Bud stage
Tooth grows inward into jaw, mesenchyme cells migrate toward bud
Bud stage, explain A and B
A= enamel organ; dental lamina
B= (ecto)mesenchymal condensation
During the bud stage is there differentiated cells?
NO! only group of condensed cells. Differentiation is in cap stage!
Marks the onset of morphologic differences between tooth germs that give rise to different types of teeth.
Bud-to-Cap transition
Explain
Cap Stage
Cap Shaped; developing tooth, contain enamel organ, cervical loop transition from inner and outer enamel epithelium.
Cervical loop grow and trap dentin
Inner= dentin
Closer to middle= pulp tissue of teeth
is a cellular aggregation seen in a developing tooth and it lies above the dental papilla.
Enamel Organ
At the periphery of the enamel organ, the cells assume a low cuboidal shape and form the
Outer Enamel Epithelium
The cells bordering on the dental papilla assume a short columnar shape and are characterized by high glycogen content
Inner enamel Epithelium
center of the enamel organ
Stellate reticulum
In the bell stage, some epithelial cells between the inner enamel epithelium and the stellate reticulum differentiate into a layer called the
Stratum Intermedium
region where the inner and outer enamel epithelia meet at the rim of the enamel organ is known as the
Cervical loop; roots
ball of condensed ectomesenchymal cells which will eventually form the dentin and the pulp of the tooth.
Dental papilla
The condensed ectomesenchymelimiting the dental papilla and encapsulating the enamel organ
gives rise to the supporting tissues of the tooth
Dental follicle
The
* enamel organ
* dental papilla, and
* dental follicle together constitute the?
Tooth germ (dental organ)
tologic slide showing a tooth bud.
What is A B C?
- A: enamel organ
- B: dental papilla
- C: dental follicle
What does this slide display?
Early cap stage of tooth development (arrows).
A = Meckel’s cartilage;
B = developing tongue
early cap
What does the cap stage start with?
cellular differentiation within the enamel organ.
early cap
During histodifferentiation in the cap stage, central cells in the enamel organ form the?
Stellate Reticulum
early cap
During histodifferentiation in the cap stage, epithelial cells differentiate into what 2 kinds of cells?
inner and outer enamel epithelia.
During the late cap stage what 5 things have formed?
- A = stellate reticulum
- B = outer enamel epithelium
- C = inner enamel epithelium;
- D = dental papilla;
- E = dental follicle (everything around cap; future pdl)
By the bell stage is the tooth type decided?
Yes!
During this stage, the cells that will be making the hard tissues of the crown (ameloblasts and odontoblasts) acquire their distinctive phenotype (histodifferentiation), and the crown completes its morphodifferentiation and attains its full size.
Bell Stage
Early bell
What is A and B?
A = inner investing layer of dental follicle;
B = outer layer of dental follicle
During the early bell stage what does the dental papilla look like in comparatison to how it was in the cap stage?
Dental Papilla is more invaginated and condensed
Early Bell
What tooth class will this be?
Incisor
is a permanent tooth that replaces a primary (deciduous) tooth.
succedaneous teeth
Permanent Incisors, Canines, and Premolars are what type of dentition?
succedaneous teeth
Note tooth bud of permanent tooth forming
What is the only class of permanent dentition that are not succedaneous?
Molars! They are brand new.
What stage of tooth dev?
Formation of buds on mandible and maxilla
Initiation
When permanent molars form do they have teeth around them? Why?
No! because they are not succedaneous. Form alone
Explain why primary teeth roots bend buccally.
In development,** primary tooth bud is buccal** and permanent tooth bud is lingual.
Review Stages of tooth Dev.
