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xD2 Genetics Final > GenF Tooth Development > Flashcards

GenF Tooth Development Flashcards

1
Q

Is dentin harder and denser than bone?

A

Yes

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2
Q

What is the process wherby a single cell becomes a differentiated organism. Also the process of orderly change that an individual goes through in the formation of structure?

A

Development

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3
Q

What are changes in cell shape and physiology associated with the production of the final cell types of a particular organ or tissue?

A

Differentiation

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4
Q

What is the process in embryonic development whereby the three primary germ layers are laid down and the gut formed through complex cell migrations?

A

Gastrulation

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5
Q

What are cells that can give rise to several other cell types, but those types are limited in number?

A

Multipotent

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6
Q

What is the potential of a cell to develop into more than one type of mature cell, depending on environment?

A

Pluripotent

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7
Q

What are the undifferentiated, primitive cells that have the ability both to multiply and to differentiate into specific cell types?

A

Stem cells

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8
Q

What is the state of a cell that can give rise to any and all adult cell types as compared with a differentiated cell whose fate is dertermined?

A

Totipotent

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9
Q

Why use mice as a model for studying human tooth development?

A
  1. Mice are vertebrate mammals whose early tooth development is similar to humans
  2. Mice have a short gestation period (3 weeks)
  3. Mouse genetics are well worked out, so we can manipulate the genome
  4. Human genes have homologues in mice
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10
Q

What stage can we only study in the mouse model organism?

A

Embryo

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11
Q

What is the disadvantage in using mouse model?

A

Only 2 teeth shapes: molars and incisors, and no canines (only a diastema in their jaw where they should be)

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12
Q

What are 4 methods to study developmental biology?

A
  1. Direct observation of developing structures
  2. Tissue recombination experiments
  3. Manipulation of organism’s genome In-situ hybridization
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13
Q

What is the dissection of tissue and implantation of the tissue into a novel location?

A

Tissue recombination experiment

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14
Q

What are 3 ways to manipulate a genome?

A
  1. Transgenic (add a gene)
  2. Knock out (delete a gene)
  3. Knock in (replace a gene)
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15
Q

What uses anti-sense RNA probes to identify where a specific gene is expressed in whole embryos or tissue sections of embryos or specific tissues?

A

In-situ hybridization

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16
Q

From what cell population are teeth and craniofacial bones derived from?

A

Transient pluripotent cell population called Neural Crest Cells

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17
Q

Where do neural crest cells form?

A

The border between ectoderm and where neural tube forms

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18
Q

What happens to these border ectodermal cells?

A

Transform into mesenchymal cells, delaminate(peel off), migrate dorsal-ventrally to branchial arches

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19
Q

How many branchial arches are there?

A

6

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20
Q

From where do the maxillary and mandibular processes arise?

A

Caudal (posterior) part of the forebrain and first branchial arch

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21
Q

The maxillary and mandibular processes are what surrounded by what?

A

Mass of mesoderm surrounded by epithelial cells

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22
Q

What is the first sign of tooth formation and is the thickening of the oral epithelium?

A

Formation of the dental lamina, which is done through epithelial signaling

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23
Q

Where does the dental lamina go and what does it form?

A

Dental lamina grows into underlying mesenchyme and forms epithelial buds

24
Q

The tooth bud is now surrounded by what and they form what?

A

Mesenchymal cells accumulate around epithelial bud and form dental papilla

25
Q

The dental papilla will form what later?

A

Dental pulp and odontoblasts

26
Q

What do the cells in the middle of the epithelial bud form?

A

Do not grow, but form Enamel Knot

27
Q

What do the enamel knots and secondary knots form and in what manner do they form?

A

Form tooth cusps through balance between cell growth and death

28
Q

The epithelial cells that surround the enamel knots proliferate, grow into the mesenchyme and undergo specific folding during cap and bell stages will eventually give rise to what cell type?

A

Ameloblasts

29
Q

What cells does the mesenchyme give rise to?

A

Odontoblasts

30
Q

The formation of specific cell types (ameloblasts and odontoblasts) is called what?

A

Cytodifferentiation

31
Q

What are 2 things that can stimulate mesenchymal cells to become cementoblasts?

A
  1. Dentin

2. Epithelial root sheath

32
Q

At what point in root formation will a tooth begin to erupt?

A

When 1⁄2-2/3 of root is developed

33
Q

Eruption of a tooth is generally complete when approximately how much of root is developed?

A

3⁄4 root (35 day old baby)

34
Q

Teeth develop through a series of what?

A

Reciprocal interactions between 2 adjacent tissues: epithelium and mesenchyme. They take turns at different stages inducing tooth formation

35
Q

How are the induction events mediated?

A

Through a series of specific developmentally regulated signaling molecules

36
Q

What is used to identify genes important in tooth development?

A

Use knockout mice. Can’t be used in humans, but a spontaneous mutation would reveal the same information

37
Q

What is a transcription factor gene that is shown to be expressed in neural crest derived mesenchyme?

A

Pax 9

38
Q

Pax9 -/- (homozygous) mice all teeth are absent and arrested in the bud stage. What does this mean?

A

Pax 9 function is required in all developing teeth before or at bud stage

39
Q

List the genes Dr. Shiang listed as being affected by Pax9.

A
  1. Bmp4
  2. Msx1
  3. Lef1
40
Q

What are 8 defects affected by genes?

A
  1. Where teeth develop
  2. Number of sets of teeth
  3. Tooth development at particular stage
  4. Development of specific teeth
  5. Transform teeth type
  6. Defects in shape and size of teeth
  7. Defective cytodifferentiation
  8. Generation of extra teeth
41
Q

What 3 gene classes are important in tooth development?

A
  1. Signaling molecules and their receptors 2. Transcription factors
  2. Genes affecting cell growth
42
Q

What is a signaling molecule gene important for tooth development?

A

Eda

43
Q

Knock-out mice that do not have Eda will have what tooth abnormality?

A

Molars with abnormal shape and size

44
Q

Which transcription factor gene is important for tooth development?

A

Pax 9 (important in bud stage), Gli2, Lef1

45
Q

What are 2 genes that affect cell growth?

A
  1. p21

2. p63

46
Q

If gene affecting cell growth, p21, is absent, what occurs in tooth development?

A

Inhibits cell proliferation in the enamel knot

47
Q

If the gene affecting cell growth, p63, is absent, what occurs in tooth development?

A

Absence of tooth primordial (whatever that means)

48
Q

How does Pax 9 affect Msx1 and Lef1 expression?

A

Through Bmp4, if no Bmp4, none of the other stuff

49
Q

What are 3 approaches for bioengineering teeth?

A
  1. Isolate epithelial and mesenchymal tissue during correct development stage
  2. Unborn baby stem cells (ES)
  3. Adult stem cells
50
Q

What is the most accessible source of postnatal stem cells found in the pulp of permanent teeth, highly proliferative, can differentiate into odontoblasts, neural progenitors, osteoblasts, chondrocytes, adipocytes?

A

Dental pulp stem cells (DPSC)

51
Q

Can we get stem cell from exfoliated deciduous teeth?

A

Yes, called stem cells from human exfoliated deciduous teeth (SHED). Can also differentiate to functional vascular endothelial cells.

52
Q

Dentally, how could the absence of the MSX1 present itself?

A
  1. Missing 2nd PM and 3rd molars
  2. Premolar hypodontia
  3. Orofacial clefts
  4. Witkop/Tooth and Nail syndrome TNS
53
Q

What is Witkop or Tooth and Nail Syndrome (TNS)?

A

Found w/ MSX1 deletion

Predominantly anterior tooth agenesis, with some posterior nail dysplasia

54
Q

Families with molar hypodontia or oligodontia wher found to have mutations in what transcription factor important for tooth development in the bud stage?

A

Pax 9

55
Q

Mutations in transcription factors likely result in what?

A

Abnormal regulation of other genes involved in tooth development

56
Q

How is a knockout created?

A

A clone of a gene is created with a portion deleted then combined with chromosomal copy in embryonic stem cell

57
Q

How does one make a whole knock out mouse?

A

Inject the knockout embryo stem cells in to embryo and implant in female. Pups will have both knockout and parent genes. Mated to get progeny of only knockout embryonic stem cells.

xD2 Genetics Final (7 decks)

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