Ex 2- Molecular + Genetic Basis of Tooth Development-- Sun Flashcards
(97 cards)
1
Q
Cranial neural crest cells the _____ germ layer
A
fourth
2
Q
_____ _____ _____ cells (NCC) are formed at the _____ of the neural tube and start migrating when the neural tube closes
A
Cranial neural crest
back
3
Q
NCC migrate a long distance through defined paths to reach the ______ _____
A
branchial arches
4
Q
NCC cells are ____ cells
A
stem
5
Q
Branchial arches (pharyngeal arches) are ridges formed on the sides of head and neck at embryo week __
A
4
6
Q
Teeth are only developed in the _____ branchial arch
A
first
7
Q
What are the 2 fates of a stem cell?
A
- replicate itself (self renewal)
2. Differentiate into varied types of mature cells
8
Q
What are the 2 divisions of stem cells?
A
Symmetric (same)- parent cell
Asymmetric (different)- differentiated cell
9
Q
NCCs are _____-____ stem cells
A
multi-potent
10
Q
NCCs can differentiate to form ectomesenchymal cells which ultimately from ______ and _______
A
odontoblasts
cementoblasts
11
Q
Embryonic development of branchial arch structures, including odontogenesis at the right location and time relies on complicated but precise ______-_____ interaction
A
tissue-tissue
12
Q
______ - _____ interaction regulates NCC cells during morphogenesis and controls the position, size, and shape of organs
A
Ectoderm- NCC
13
Q
______ - _____develops pharyngeal pouch generated organs: thyroid, parathyroid, and thymus
A
Endoderm- NCC
14
Q
______ - _____ provides environment for NCC cells to populate
A
Mesoderm-NCC
15
Q
NCCs form well-organized _______ ______ to the branchial arches
A
migratory streams
16
Q
NCCs for the first branchial arch are from hindbrain rhombomeres r__-__
A
1-2
17
Q
How many rhombomeres are there in the hindbrain?
A
7
18
Q
Hindbrain-derived neural crest cells migrate in ___ streams: Arch 1, 2, 3
A
3
19
Q
1st branchial arch is from rhombomeres r __ - __
A
1-2
20
Q
2nd branchial arch is from rhombomeres r __
A
4
21
Q
3rd branchial arch is from rhombomeres r __ - __
A
6-7
22
Q
Rhombomeres ___ and ___ undergo apoptosis creating a barrier
A
3 and 5
23
Q
The branchiomotor nerves collect axons from cell bodies but exit the hindbrain only from the _____ numbered segments to innervate their peripheral target structures
A
even
24
Q
_______ nerve is associated with r __-__; 1st branchial arch structures including ______
A
Trigeminal (V)
1-3
teeth
25
______ nerve is associated with r4-5 the 2nd branchial arch
Facial (VII)
26
_______ nerve is associated with r6-7 the 3rd branchial arch
Glosopharyngeal (IX)
27
NCCs in each migratory stream express specific _____ ____ codes
Hox gene
28
_____ ____ are a group of homeobox genes, which possess a unique homeobox (DNA sequence) which encodes a conservative homeodomain (protein segment)
Hox genes
29
If a Hox gene is expressed, its protein product functions as a _______ ______ which controls other gene expression
transcription factor
30
NCCs involved in tooth development (1st branchial arch) do NOT express _____ _____. They carry the genes but don't express them
Hox genes
31
NCCs that migrate to the ___ branchial arch start expressing Hox gene
2nd
32
Within the first branchial arch, specific ____ ____ codes are expressed to produce differences between he maxilla and mandible
Dlx gene
33
Dlx genes another ________ gene expressed as _____ ______. 7 members in family. 4,7,8,9 are same gene
homeobox
| transcription factors
34
Dlx __/__ combination is required for development of the proximal portion of first branchial arch (maxillary process)
1/2
35
Dlx 1/2 double mutants lack ALL _______ _____ while all mandibular structures are not affected
maxillary molars
36
Dlx __/__ combination is required for development of the distal portion of 1st branchial arch (mandibular process)
5/6
37
Dlx 5/6 double mutants develop lower jaws like mirror images of the ________ jaw
upper
38
Normal tooth development is a process with precisely arranged/regulated _____ and ____ interactions
cell and molecular
39
Interaction between the epithelium and the _______ is through the entire process of tooth development
mesenchyme
40
Cranial neural crest cells directly contribute to the development of dentin, cementum, pulp and periodontal ligament but not to _____
enamel
41
What are the four major signaling pathways for the ectoderm-derived epithelium?
- BMP; bone morphogenic protein
- FGF: fibroblast growth factor
- Wnt: wingless
- SHH: sonic hedgehog
42
All four molecules (BMP, FGF, Wnt, SHH) bind to the _____ ______ ____ and eventually impact on gene regulation through varied ______ _______
cell membrane receptors
| intracellular pathways
43
These molecular signals are also important for the development of other _______ organs such as hair, nails, and glands
ectodermal
44
______ ____ are epithelial aggregates that function as ______ ______ for tooth morphogenesis and odontoblast differentiation
enamel knots
| signaling centers
45
_______ enamel knot appears at the end of the bud stage and is essential for bud-to-cap stage transition, without it, tooth development will be arrested
primary
46
_______ enamel knot appears at the locations of future molar cusps at the bell stage and determine the _____ and ____ of molar cusps
secondary
number
locations
47
The ______ enamel knot closely interacts with the mesenchyme
primary
48
The ______ enamel knot stimulates terminal differentiation of odontoblasts at the end of the bud stage, which always occurs first at the location of future cusp tips
secondary
49
The ________ enamel knot stimulates proliferation of adjacent cells
primary
50
The ______ enamel knot disappears by cell apotosis
primary
51
The ______ enamel knot is not present in incisors
secondary
52
Differential expression of signaling molecules in the enamel knots determine _____ patterns
cusp
53
_____ may function as a cusp activator while ____ (possibly Shh also)may function as the inhibitor to regulated the formation of _____-_____distance
FGF
BMP
inter-cusp
54
What are the important signaling molecules that are produced by the mesenchymal cells for tooth development?
BMP
FGF
Wnt
+ their inhibitorss
55
What are the important transcription factors produced by the mesenchymal cells for tooth development?
```
Msx 1/2
Dlx 1/2
Pax9
Gli 2/3
Runx2
Barx1
```
56
At the cell and molecular level, the development of tooth crown can be divided into what 3 major stage?
1. Initiation
2. Morphogenesis
3. Differentiation + Mineralization
57
Which signaling molecules are present at the anterior sites which control the development of incisors?
BMP4
Msx1
Msx2
58
Which signaling molecules are present at the posterior sites which control the development of molars?
FGF
Barx1
Dlx2
Lhx6/7
59
Innervation of the tooth is from what cranial nerve?
CN V (Trigeminal)
60
Pioneer trigeminal axons penetrate into the dental pulp after the start of enamel formation during the _____ stage
Bell
61
______ serves as a chemorepellent for the axons, thus controlling the timing and patterning of tooth innervation
Sema3A
62
Through the epithelial-mesenchymal interaction, epithelium expresses what into mesenchyme?
Sema3A
63
After the crown development is nearly complete, the ______ ______ _____ grows apically between the 2 mesenchymal regions; dental papilla + dental follicle
Hertwig's root sheath (HERS)
64
After HERS formation _______ _____ appear adjacent to the HERS on the papilla side
apical odontoblasts
65
Although enamel is not present in the final root, induction from the ______ is required for root development
epithelium
66
______ develops before ______ in terms of parts of the tooth
crown
| root
67
HERS induces dental papilla to differentiate into _____ _____
apical odontoblasts
68
________ secreted by HERS induces odontoblast differentiation
lamini-5 + transforming growth factor-beta (TGF-B)
69
_______ _____ ___ is essential for root dentin formation but not for crown dentin formation. Without this odonotblast cannot develop normally even when HERS is normal
Nuclear factor Ic (Nfic)
70
Odontoblasts in the _____ region are much less elongated than those in the _____ regions
root
| crown
71
Cementum formation starts when ____ and ____ ______ cells are in close proximity (relative contributions unclear)
HERS
| dental follicle
72
What molecules are involved in epithelial-mesenchyme interaction?
- HERS: TGF-B, Nfic, Insulin like growth factors, Wnts, FGF
| - Mesenchyme: BMP, FGF
73
HERs determine the ______ of roots
number
74
_____ do not respond to signals from the mesenchyme an do not differentiate into ameloblasts
HERs
75
Most molecules involved in crown and root development are _______
different
76
______ ______ syndrome is when two or more ectodermal structures are affected
Ectodermal dysplasia
77
Mutations in transcription factor _____ causes ______ ____ but normal function is requried fro the normal function of FGF, BMP, SHH, critical signaling pathways involved in epithelial-mesenchymal interaction
p63
| ectodermal dysplasia
78
_____ mutation results in multiple family members lacking both maxillary premolars and mandibular 2nd premolars
Msx1
79
Msx1 mutation is caused by __ to ___ transversion in the homeodomain region affecting its normal transcription factor function
G
| C
80
_____ mutations cause people to have no molar development and is caused by a _______ insertion that causes a frame shift in the DNA binding domain affecting its normal transcription factor function
Pax9
| guanine
81
______ mutations cause affected members to have more than 8 permanent teeth underdeveloped
Axin2
82
Axin2 mutations are caused by missence (C-->T) or insertion (G) mutations that introduce a premature _____ codon in the gene
stop
83
Loss of Axin2 function disrupts the ______ signaling but Axin2 does NOT function as a transcription factor. Prone to colorectal polyps + cancer
Wnt
84
____ mutation causes multiple missing anterior teeth (__-linked dominant)
EDA
| X
85
EDA muation is caused by missence (C-->G) resulting in Q to E substitution disrupting the transmembrane signaling molecule belonging to the ____ family but does not function as a transcription facotr
TNF
86
What are the theories of etiology of supernumerary teeth?
- Atavism
- Tooth germ dichotomy
- Hyperactivity of dental lamina
* Genetic + environmental factors
87
Most supernumerary teeth are isolated cases. ______ supernumerary teeth are rare but can happen in certain ______ conditions
Multiple
| systemic
88
______ _______ syndrome is an autosomal-dominant skeletal displasia in clavicles, patent sutures, and fontanels, formation of Wormian bones and short stature results in supernumerary teeth and delay eruption of permanent teeth
Cleidocranial dysplasia
89
_______ mutations causes clleidocranial dysplasia and encodes a transcription factor
Runx2
90
Runx2 is a ______ regulator of primary teeth and a _____ regulator of secondary teeth
positive
| negative
91
Identical Runx2 mutations showed what in supernumerary tooth formation
wide variation: suggesting epigenetic + environmental factors play a role
92
_______ syndrome causes adenomatours polyps of the GI tract, desmoid tumors, osteomas. Dental anomalies: supernumerary teeth, impacted teeth, dentigerous cysts
Gardner
93
____ gene mutation causes Gardners's syndrome is a signaling molecule NOT TF
APC
94
APC deficiency is mediated by ___-____
B-catenin (wnt pathway)
95
What genes encode transcription factors?
Msx1
Pax9
p63
Runx2
96
What genes encode signaling molecules?
Axin2 (Wnt pathway)
EDA (TNF pathway)
Apc (Wnt pathway)
97
What gene mutation are related to supernumary teeth?
- Runx2- Cleiodocranial dysplasia syndrome
| - Apc- Gardner's sydrome
