Body Axes and Neurulation Flashcards

1
Q

Cell migration and specification (gastrulation) are controlled by what?

A

FGF8 (made by primitive streak cells)….establishes expression of Nodal on LEFT side only (before gastrulation it’s symmetric)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Primary germ layers

A

Top to bottom:

Ectoderm
Mesoderm
Endoderm

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What expresses genes for head formation and TF’s “cerebrus” and “lefty”?

A

AVE (anterior visceral endoderm)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Gene for movement of cells from primitive streak

A

Brachyury (T) gene

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Gene for primitive streak formation

A

Nodal gene

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Gene for body axis formation

A

Goosecoid gene

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Gene for the formation of notochord

A

HNF-3β

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Gene for head formation

A

Lim-1

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Goosecoid gene overexpression

A

2 heads

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What does T gene (brachyury) antagonize?

A

BMP-4

Absense of T (brachyury) gene → no lower body/very small

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Activin gene inhibits what and is expressed on which side?

A

Inhibits Shh (sonic hedgehog) expression

Activin expressed on RIGHT, so it blocks Shh on the right

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

FGF8 induces expression of what?

A

Lefty2 (Lefty 1 expressed in forming neural tube)

5HT dependent on serotonin

5HT→FGF8→Nodal and Lefty2→PITX2

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

PITX2 does what?

A

TF responsible for establishing LEFT sidedness (defects can cause organs to be on opposite sides)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

5HT is important in what?

A

Establishing laterality

Disruptions can result in situs inversus, dextrocardia and heart defects

↑ congenital heart defects in children born to mom’s who take antidepressants from selective serotonin reuptake inhibitors (SSRI’s)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Gene for Right-sided development

A

Snail

repressed by Nodal

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What blocks BMP-4?

A

Noggin
Chordin
WNT3a
FGF

If BMP4 is present: Ectoderm → Epidermis
If BMP4 is BLOCKED: Ectoderm → neural plate

17
Q

Epidermis has a lot of what?

A

BMP4

It’s going to induce a new signaling center in roof plate

18
Q

What transcription factor induces a floor plate in the ventral floor of neural tube?

A

Shh (Sonic hedgehog)

19
Q

What is Rachischisis?

A

Neural tube defect

Neural tube fails to close during week 4 of development

Most severe form of spina bifida. Causes paralysis from the level of the defect and caudally

20
Q

What is neurulation?

A

Refers to the formation and closure of neural tube

21
Q

What is Anencephaly?

A

Cranial Neuropore fails to close (on the head)

22
Q

What is Encephalocele?

A

Failure of back of head to close (occipital region)

Anterior (frontal) Encephalocele: failure on front of face to close

23
Q

Spina bifida with meningomyelocele

A

Large skin-covered bulge at posterior lower lumbar spine. There is also paralysis of the baby’s legs

24
Q

What causes lifelong paralysis from Spina Bifida?

A

If it isn’t fixed before 38 weeks

25
Q

How does folic acid prevent neural tube defects?

A

Daily intake of 0.4mg of folic acid (folate) will decrease the odds of it

Prevents 70% of human neural tube defects (NTD’s) but mode of action is unclear

26
Q

An increase of what appears to prevent the closing of the neural tube?

A

Increased homocysteine levels

  • Tested by alpha-fetoprotein (AFP)
  • AFP is made in liver. With NTD, AFP leaks into amniotic fluid across the placenta. Maternal blood can be tested for OPEN tube defects only
27
Q

What does BMP do?

A

Induces the neural crest

Abnormal concentrations of BMP/FGF’s → neural crest defects

BMP, FGF, WNT proteins → induce PAX3 to “specify” the neural plate border

SNAIL and FOXD→specify cells as neural crest

SLUG → promotes crest cell migration from neuroectoderm

28
Q

Ectodermal dysplasia (ED)

A

Affects the ectoderm (outer layer of tissue in developing baby)

When child has 2 types of abnormal ectodermal features- malformed teeth, sparse hair etc

29
Q

What does the Lateral Mesoderm differentiate into?

A

Appendicular skeleton, dermis of skin

30
Q

Pigmentary Disorders: Vitiligo

A

Loss of melanocytes

spotchy