Molecular and Genetic Mechanisms of Tooth Development (Larsen 3) Flashcards
Cell fate depends of _____ and ______.
- Origin
- Temporal-spatial history
Cell fate is determined by _____ and ______.
-Genes
-Environment
(Autonomous or intrinsic) (Non-autonomous or extrinsic)
What combination of epithelium and neural crest cells results in tooth formation?
- Neural crest
- Mandibular epithelium
Prior to day 12, the _____ initiates odontogenesis.
Epithelium
After day 12, the mandibular/first arch epithelium _____ odontogenic potential and _______ directs the development of the tooth.
- Loses
- Ectomesenchyme
Growth factors are _____.
Peptides
Growth factors bind to _____ in membrane which initiates a cascade of specific protein-protein interactions.
Receptors
Transcription factors bind to ______ and a gene is transcribed to make mRNA allowing specific proteins to be translated.
DNA
Initiation (_____) –> Morphogenesis (____, ____) –> Cytodifferentiation (____)
- Dental lamina
- Bud, Cap
- Bell
Undifferentiated ectomesenchymal cells become ______ when in contact with _____.
- Odontoblasts
- Growth factor
Co-linear-spatial relationship on the chromosome is the same as the embryo anteroposterior axis. These genes are called ______.
Hox genes
Each Hox gene contains a ________.
Homeodomain
Hox family genes establish regional diversity within the ________.
Brachial arch system
What are the homeobox genes associated with the neural crest cells migrating from the midbrain and rhombomeres 1 and 2
- Msx
- Dlx
- Barx
The formation of the dental lamina occurs in the overlap region of the _____ that expresses _____, _____, and _____.
- Ectomesenchyme
- Msx-1
- Msx-2
- Dlx-2
During the formation of the dental lamina, expression is induced by _____ and repressed by _____ from epithelium.
- Fgf-8
- Bmp-4
Homeobox Expression: Incisor
- Msx-1
- Msx-2
Homeobox Expression: Canine
- Msx-1
- Msx-2
- Dlx-2
Homeobox Expression: Molar
- Dlx-2
- Barx-1
_____ gene expression occurs at sites where tooth germs appear.
Co-localized
What controls the number and marks the position of teeth? (Epithelium)
- Fgf-8 induces
- Bmp-2 and Bmp-4 restricts
- FGF does not overlap with BMPs location (how placode forms)
What controls the number and marks the position of teeth? (Ectomesenchyme)
- Pax-9
- Depends on ligands early and independent from bud stage on
Roles of epithelium and ectomesenchyme ______ during tooth development.
- Change
- Early: epithelium is in control
- Once mesenchyme specification is established, the mesenchyme takes over
Initiation: Epithelial Signals
Shh (sonic hedgehog) a secreted protein
-Shh soaked beads applied to oral epithelium causes invaginations that resemble tooth buds
(Direction of Signals E–>M)
Bud Stage: Condensing Mesenchyme Signals
The switching of the expression of BMP-4 indicates the control shift of tooth development from the epithelium to the connective tissue
(Direction of Signals M–>E)
Dental lamina expresses _____ where teeth will develop during the initiation stage, down growth of the dental lamina.
BMP-4
During the morphogenic (bud) stage, BMP-4 expression is switched to the _______.
Connective tissue
Changes in BMP-4 expression precedes changes in _____ expression which becomes more localized.
Msx-1
In the Cap Stage (Enamel Knot Signaling), ______ is required to induce the enamel knot.
Mesenchymal Bmp4
Direction of Signals E–>M
In the Cap Stage (Enamel Knot Signaling), specific inner enamel epithelium cells express ____, ____, and ____.
- SHH
- BMP4
- FGF4
A layer of non-dividing ______ at the surface of the developing _____ controls the crown shape
- Epithelium
- Cusp tips
What is involved in formation of crown shape?
- Primary enamel knot
- Secondary enamel knot
- Express p21 (cell cycle related gene)
- Signaling factors: BMP, FGF, SHH, WNT
Gene name and function: Msx
- Msh-like genes
- Transcription factor
Gene name and function: Dlx
- Distaless homologue
- Transcription factor
Gene name and function: Barx
- Barh1 homologue
- Transcription factor
Gene name and function: Bmp-4
- Bone morphogenetic protein
- Secreted protein
Gene name and function: Shh
- Sonic hedgehog
- Secreted protein
