Odontogenesis: cellular and Molecular Flashcards
1
Q
number of chromosomes in people
A
22 pairs of autosomes
1 pair of sex chromosomes
2
Q
Germ cells
A
Gametes (spermatozoa and ova)
3
Q
what do gametes hold
A
1 chromosome from each pair of chromosomes
4
Q
DNA that encodes a protein product
A
Gene
5
Q
Genomic DNA is converted to mRNA in the nucleus
A
Transcription
6
Q
mRNS serves as a template for making a protein out of amino acids in the cytoplasm
A
Translation
7
Q
Different versions of the same gene
A
Allele
8
Q
Genetic makeup of an individuals (what alleles do they carry)
A
Genotype
9
Q
Observable characteristics from the genotype and envrionment
A
pHenotype
10
Q
A change in nucleotide sequence of a gene
A
Mutuations
11
Q
Mutation in germline is what
A
Heritable and passed to offspring
12
Q
A hereditary disease that affects bones and teeth
A
Osteogenesis imperfecta (OI)
13
Q
what is mutatated in Osteogenesis Impoerfectta
A
COL1A1 (type I collagen)
14
Q
what type of mutation is Osteogenesis imperfecta
A
Autosomal dominant
15
Q
what is the result of an autosomal dominant mutation
A
1 mutant allele is enough to cause OI phenotype
Shows up in nearly every generation (50% of chance in offspring)
16
Q
what kind of disease is Supernumerary incisor
A
Autosomal recessive
17
Q
what is needed for autosomal recessive diseases to show in the phenotype
A
2 mutant alleles to change phenotype
18
Q
how does Autosomal recessive diseases show
A
not every generation, as both parents need to at least be a carrier of the gene
19
Q
the processes of a generalized cell become specialized for a job
A
Cell differentiation
20
Q
what changes in cell differentiation
A
size, shape, products, activities, divisions
21
Q
what is the product that initiates differentiation
A
induction
22
Q
an agent that procides cell with a signal to differentiate
A
Inducer
23
Q
what must a cell be to respond to an inducer
A
must be competent to receive the signal
24
Q
the ability of a cell to receive and respond to a molecular signal
A
Competence
25
what is needed for cellular competence
Receptors
| Internal machinery
26
what inducer binds to cell surface BMP receptor type I or II
Bone Morphogenetic protein (BMP)
27
what inducer binds to intracellular vitamin D receptor
Vitamin D
28
What inducer binds to cell surface LRP6 and Frizzled Receptor
WnT signal
29
what is cell signaling
Transfer of information to cuase change in cell gene expression and function
30
what are some cell signals
Signals
Growth factors
Inducer
Ligand
31
types of cell signaling receptors
Membrane
| Intracellular/nuclear
32
what happens in cell signalling
Inducing signal comes from outside cell
Cell is competent to receive it
Intracellular changes
Cell function changes
33
Effects of cell signaling
Cell Differentiation
Cell Proliferation
Cell Migration
34
what is cell signalling
Secreted chemical signal directs changes in target cells that express receptors
35
what controls gene expression
Transcription factors
36
what are transcription factors
Proteins that control whether genes will be transcribed into mRNA
37
how many genes can one TF control
tens to hundgreds of genes
38
what do TF do for target genes
can activate or repress expression
39
what are Pleiotropic effects
1 mutations causes lots of systems to be affected
40
Amino acids in the DLX family
214 amino acid TF
41
what does a a mutation in DLX3 lead to
Pleiotropic effects
42
what does DLX3 regulate
Hair folicle differentiation (BMP signaling)
Enamel genes (Amelogenin, Enamelin, Kallikrein 4)
Bone (formation, resporption, hemostasis)
43
what mainly happens in weeks 0-4 of development
mostly proliferation and migration
44
what happens in week 4 to 8
cell differentiation
| Morphogenesis
45
Formation of major external and internal structures
Morphogenesis
46
what happens in week 8 to 40
Growth and maturations
47
what are the 2 stages of prenatal development
Embryo(0-8 week)
| Fetus(8-40 week)
48
the inner cell mass of the Blastocyst stage
Embyroblast
49
what does the Embryobalst form
All tissues of the embryo
50
what are the cells of the embryoblast
Embryonic stems
51
the outer cells of the blastocyst
trophoblast layer
52
when is the Morula
3-4 days
53
what does the Blastocyst form
day 5-13
54
what are the layers of the Bilaminar embryo
Ectoderm- dorsal
| Endoderm- ventral
55
what do he ectoderm cells look like
Columnar cells
56
What do the endoderm cells look like
More cuboidal
57
how does the mesoderm form
Ectodermal cells converge to the midline to form the primitive streak
Extoderm migrate through the streak between the ectoerm and endoderm to create the mesoderm
58
what is the conversion to a trilaminar embryo
Gastrulation
59
when does gastrulation occure
3rd week
60
what layers make up the buccopharyngeal membrane
Extoderm and endoderm without any mesoderm
61
what eventually forms the notocord
Cephalic (more rostal) migrating cells
62
when does Rostro-caudal(front back) folding occure
week 4
63
why does Rostro-caudal folding occur
directed growth at both ends
64
when does lateral (side to side) folding occure
week 4
65
what happens in lateral fodling
middle parts grow upwards and close to form the neural tube and neural crest cells
lateral parts of the ectoderm grow downwards to sournd the endoderm
66
what does Rostral-caudal folding form
A mouth
67
The primitive oral cavity
Stomatodeum
68
what defines the most rostral boundry of the primitive gut
Buccopharyngeal membrane
69
what origin are neural crest cells
Extoderm
70
where are neural crest cells formed
Adjacent to neural tube to separate from the neural plate when the neural tube closes
71
when does the neural tube close
day 22/end of 3rd week
72
what do the Neural crest cells do
Migrate and differentiate extensively
73
what do Cranial Nueral crest cells undergo
Epithelial- mesenchymal transformation
74
other name for Crnail neural crest cells
Ectomesenchymal cells
75
why are Cranial neural crest cells also called ectomesenchymal cells
Act like mesenchyme to form the connective tissues of the head
76
what part of Cranial neural crest cells is important to dentist
Create the connective tissue of teeth and supportive tissues
77
why are neural crest cells important
```
Become some of the craniofacial bones
Cranial and sensory ganglia and nerves
Adrenal medulla
dentin
Periodontal ligaments
Alveolar bonds
```
78
where do skeletal bones come from
Mesoderm
79
where do Neural crest cells populate
head and oral cavity
80
what does the neural tube do during brain development
expands to become to forebrain, midbrain, and hindbrain
81
what does the hindbrain form
8 rhombomeres (buldges)
82
what do the Rhombomeres define
the origins of distinct populations of NCCs
83
what controls Neural crest cell migration
Tightly controled by signals
84
what neural crest cells contribute to branchial arch 1
From midbrain and Rhombomeres 1 and 2
85
First stream of neural crest cells from the midbrain and rhombomeres 1 and 2 contibute to what
The embryonic connective tissue of the face
86
the second stream of neural crest cells from the midbrain and rhombomeres 1 and 2 contibute to what
the embryonic connective tissues of the First branchial arch
87
what do Rhombomeres 3 and up contribe to
To other strucutures not the face or 1st branchial arch
88
what Rhombomeres express Hox TFs
NCC from rhombomeres 3 and up
89
what are Hox TF genes
Ancient rostral-caudal patterning genes that define body segments
90
why does the Craniofacial region not have Hox genes
it is a more recent evolutionary strucutre so it has its own set of TFs
91
what are Hox Free NCCs
NCCs that migrate from mid-brain and rhombomeres 1 and 2 to the face and first brnachial arch
92
what do all transciprtion factors include
a DNA binding domain that allows them to interact with genes
93
what is included in Homeobox TFs
Have a specific 180 base pair homeobox with specific sequences
94
what are HOX TFs a part of
a subset of Homeobox genes that are very ancient body patterning directors
95
what are the NCC body patterning Genes
The head organizes (NO HOX)
96
what patterning TFs direct craniofacial development
Otx2: orthodenticle homeobox 2
Msx: muscle segment homeobox
Dlx: Distal-less homeobox
Barx: barH-like Homeobox
97
what do NCCs contribute to in the branchial arches
Contribute to the mesoderm
98
what separates arches externally
Groove/cleft
99
What is the internal depression on a arch
Pouch
100
what makes up the the arch
NCC, mesoderm
101
what makes up a groove
Ectoderm
102
what makes up a pouch
Endoderm
103
what does Brnachial arch/groove//pouch 1 make
Mandible and maxialla (teeth)
| Outer and middle ear
104
How do we understand the head organizer genes
Mutate mice (Dlx1/2) to show that altered craniofacial morphology and lack of maxillary molars
105
what does Dlx1/2 affect
teeth in maxillary process of BA1
106
what is treacher-collins syndrome
Underdeveloped craniofacial region and mandible
107
what causes Treatcher-collins syndrome
Failure/impairment of NCC migration to facial region due to a mutation in TCOF1, POLR1C, or POLR1D
108
what drives tooth formation
Epithelial-mesenchymal interactions
109
why is understanding tooth formation important
The epithelial-mesenchumal interactions for formation is conserved for many extodermal organs (hair, mammary gland, Feathers)
110
stages of ODontogenesis
Placode - bud - morphogenesis
111
what is essential for a tooth organ to form
Both adjacent tissues are essential for proper formation
112
what kind of signalling is done in Epithelial-mesenchymal sinaling
Reciprocal
Reiterative
Sequential
113
what is Reciprocal signalling
E-M signals back and forth
114
Reiterative signalling
Cells use same signaling pathways again and again at different stages
115
What are the major signalling pathways for Epithelial-mesenchymal signaling
BMP, FGF, SHH, WNT
116
what is sequential signalling
Orderly sequence of events determine whether cells are ready to receive the signal and how they respond
117
when does the stomatodeum develop
26th day
118
when does Odotogenic epithelium form
27th day
119
what are the nasal pits bound by LNP, MNP
34th day
120
when is fusion of the face complete
38th day
121
when does the processses of fusing occure with the dental lamina stage initiating odontogenesis
6th week (36 day)
122
what happens with the primary epithelial band forms
Proliferation of epithelial cells
Altered orientation of axis of division
Formation of dental lamina and 20 dental placodes
123
what is the dental lamina
Odontogenic bands
124
what are dental placodes
Local thickening of ectoderm for primary teeth
125
what is the main thing that occurs in the dental lamina
Proliferation
126
what tissues hold the odontogenic potential for the dental lamina stage
First epithelial factors direct odontogeneis ( we'll make a tooth)
then mesenchymal signals take over ( we'll make a molar)
127
what happens if you combine odontogenic epithelium with 2nd BA mesenchyme
Together they still form a tooth
128
If you combine molar mesenchyme with incisor epithelium
Form a molar shaped tooth
129
what are the theories for tooth type determination
Field model
| Clone theory
130
what is the field model for tooth type determination
```
Epithelial signals (BMP, FGF) induce mesenchymal expression of TFs
Mesenchymal TF expression in overlapping domains
```
131
what is the clone theory of tooth development
Each tooth type is derived from a close of mesenchymal cells programmed by epithelium
When close of cells reaches a critical mass, a tooth bud initiates
Next bud does not initiate until clone moves outside of inhibitory zone
132
what occures in the bud stage of odontogoensis
Down growth of dental lamina into a bud
| Up growth of mesenchyme packing into a condensation
133
what occurs mainly during the bud stage
Proliferation
134
what is the condensed ectomesenchyme in the cap stage
Dental papilla
135
what is the surrounding ectomesenchyme in the cap stage
Dental follicle
136
what occurs in the cap stage of odontogenesis
PRoliferation and morphogenesis
137
What is part of the tooth germ
Enamel organ
Dental follicle
Dental papilla
138
what is the signaling in the cap stage
The Piary ENamel knot
139
what mkaes up the primary enamel knot
Non-dividing enamel organ cells in the cap stage
140
what does the Primary enamel knot express
Numerous signaling molecules
141
what does the Primary enamel knot direct
Proliferation of surrounding epithelial cells
142
what is the Primary enamel knot essential for
Bud to cap transition by regulating cap morphology
143
why does the Primary enamel knot dissappear
Apoptosis
144
Components of the enamel organ at the bell stage
Outer enamel epithelium
Inner enamel epithelium
Stratum intermedium
Stellate reticulum
145
what type of cells make up the outer enamel epithelium
Cuboidal cells
146
what type of cells make up the inner enamel epithelium
Columnar cells
147
what cells make up the stratum intermedium
2-3 cells thick layer adjacent to IEE
148
what cells make up the stellate reticulum
Star-shaped cells with spaces between them
149
what occures during the bell stage
Proliferation
Morphogenesis
Differrentiation
150
what does the signaling in the bell stage
Sexondary enamel knots
151
what is the secondary enamel knots
Non-dividing enamel organ cels in the bell stage that appear at the sites of cusps(not th incisors)
152
what do Secondary enamel knots express
Signaling molecules (FGF4)
153
what do the secondary enamel knots do
Direct proliferation of surroudning epithelial cells, IEE completes folding, determines number and location of cusps
154
what does the secondary enamel knot stimulate
stimulates terminal differentiation of odontoblasts to begin dentinogenesis
155
where does Dentinogenesis begin always
at the cusp tip
156
Dental Papilla becomes
Odontoblasts
157
IEE becomes
Ameloblasts
158
where are the zone of maturation
the very cusp tip
159
Anodontia
Absence of all primary or secondary teeth (tooth agenesis)
160
Oliogodontia
6+ missing teeth
161
Hypodontia
1-5 missing teeth
162
Hyperdontia
More than the normal number of teeth
163
why do dental anomalies exist
Disruption in epithelial or mesenchymal function in early stages of odonotogensis
164
what causes Oligodontia
Autosomal dominant mutation in PAX9 transcription facts
165
where is PAX9 expressed
In dental mesenchyme early in development
166
what are people with oligodontia missing
Missing maxillary and mandibular 2nd and 3rd molars (incisors less affected)
167
the mineralized tissues in the oral cavity
Enamel, dentin, cementum, bone
168
The process of making a composite material
Biomineralization
169
the organic component of enamel
Enamel-specific Proteins
170
The inorganic component of all things in the oral cavity
Hydroxyapatite
171
CElls for the enamel
Ameloblasts (ectodermal)
172
Organic component of dentin
Collagen
173
Organic component of cementum
Collagen
174
ORganic component o bond
Collagen
175
Cells of the dentin
Odontoblasts(mesenchymal)
176
Cells of the Cementum
Cementoblasts (mesenchymal)
177
Cells of bone
Osteoblast (mesnchymal)
178
what makes up 90% of the matrix of dentin, cementum and bone
Type I collagen
179
what directs mineral initation,deposition, and growth in dentin, cementum, and bone
Fibrillar collagens
180
Shape of HAP in bone dentin, and cementum
Plate like "habit"
181
Length and width of Bone, dentin, cementum HAP
W: 12-20nm
L: 20-50 nm
182
shape of enamel HAP
Elongated
183
width and length of Enamel HAP
Greater the 10x W and L
184
wy is biomineralization highly regulated
Don't want Ca and P to be in blood and tissues
Need to trasnport ions to site of mineralization
Deposite extracelular matrix
hard tissue removal/remodeling
185
what is the roll of other matrix proteins in biomineralization
Positively and negatively regulate mineral initiation and growth
186
Result of Biomineralization regulation loss
Hypomineralization (Too little mineral)
| Hypermineralization (ectopic Mineral)
187
Hypomineralization leads to
Poor bone growth
Thin, weak bones and teeth
Fractures, abscesses...
188
Hypermineralization leads to
Inappropriate mineralization of soft tisues
Debilitating and lethal
FTC and ACDC/CALJA
189
the ability to differentiate to all 3 germ layers
Pluripotent
190
Pros of Embryonic stem cells
Pluripotent
Divide indefinitely
can make any tissue and repair any defect
191
cons of embryonic stem cells
Control induction
Teratoma tumor formation
Ethical concerns
192
The ability to differentiate within lmits
Multipotents
193
Pros of Adult stem cells
Ability to make several types of tissues
| Easier to control
194
Cons of Adult stem cells
Only Multipotent
Divide asymmetrically (not indefinitely)
quality and quantity decrease with age
195
where are dental stem cells found
Dental pulp
Deriodontal ligament
Dental follicle
Apical papilla
