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Block 5; Week 4 > Development-vonBartheld > Flashcards

Development-vonBartheld Flashcards

1
Q

What is the sequence of neural development?

A 
neural induction-->
neural tube formation-->
generation of neurons & glia-->
axon growth from neurons-->
synapses made with targets-->
dendrite growth-->
myelination
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2
Q

How do you get the 3 germ layers developmentally?

A

epiblast cells invaginate thru the primitive streak.

Then you get ectoderm, mesoderm, and endoderm

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3
Q

Describe the basic sequence of neurlation (neural tube formation).

A

ectoderm thickens in the middle & forms a neural plate
then you get a neural groove
the dorsal edges align & fuse–>get a neural tube!
Note: the neural tube first forms in the central part (from bird’s eye view) & then zips caudally & rostrally.
Somites form on either side.
By day 23, caudal & cranial neuropores have formed.
By day 26, neurelation is complete.

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4
Q

What induces the ectoderm to become a neural plate?

A

this induction happens via the notochord underneath the ectoderm.

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5
Q

What is the equivalent of the notochord in amphibians? This was used in experiments to figure out the role of the notochord in neural plate induction.

A

the equivalent is the organizer in the dorsal region of the amphibians.

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6
Q

What does an organizer usu do in an amphibian?

A

generates axial mesoderm during normal development.

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7
Q

Who dated Hans Spemann?

A

von Bartheld’s grandfather’s sister. : )

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8
Q

What is the default fate of the ectoderm? What stops this?

A

Default: become neuronal

BMP4 inhibits this.

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9
Q

T/F In addition to BMP4, there are a large number of molecules that regulate different parts of the neural tube.

A

True.

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10
Q

T/F Different transcription factors code for different parts of the neural tubes.

A

True.

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11
Q

Where are neurons generated developmentally?

A

they are generated in the ventricular zone

the ventricular zone is made of the neuroepithelial layer that borders the neural tube.

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12
Q

When does neural tube closure happen? What is the clinical significance of this?

A

early 4th week
so a woman could be 22 days pregnant w/o even knowing it…then she could have the problem of teratogens affecting the neural formation of her baby.

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13
Q

What is spina bifida occulta?

A

this happens when the vertebral arches of the bone don’t form properly.
happens in up to 5% of the population

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14
Q

What is a meningocele?

A

this happens with prolapse of the subarachnoid space
this can happen at the spinal or cranial level
even tho the neural tube is still intact, you need surgery.

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15
Q

What is a meningomyocele?

A

this is where the spinal cord is prolapsed into outer space, white matter may be protruding

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16
Q

What is rachischisis (no fold & fold)?

A

this is where you have no neural tube

the neural tissue that is overlying can be folded or not

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17
Q

What is a clinical sign of spina bifida occulta?

A

tufts of hair on lower back

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18
Q

What are 2 tragic neural tube defects that are not compatible with life?

A

cranial meningomyelocele

anencephaly

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19
Q

T/F Pts with anencephaly don’t have any brain structures.

A

False. They don’t have a telencephalon. They do have a brainstem, and thus can be born & live for several days.

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20
Q

What is the most common human malformation?

A

neural tube defects

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21
Q

What is the incidence of NTDs?

A

1-8/1000 live births

**incidence has been more recently reduced b/c of abortions after detection of NTD

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22
Q

What is the etiology of NTD?

A

failure of the neural tube to close

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23
Q

What is the cause of NTD?

A

multifactorial

could be chromosomal, diabetes, teratogens, hyperthermia

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24
Q

What types of meds should you NOT take if you are pregnant (capable of causing NTDs)?

A 
epilepsy meds
acne meds (Vit A high)
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25
Q

What are some things that can help in detection of NTDs?

A

ultrasound (detects anencephaly especially)

alpha fetoprotein

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26
Q

What is something that helps in prevents of NTDs?

A

folic acid!
-this has a 72% reduction power in incidence of NTDs
now we have fortified flour w/ folic acid in it etc.
-prevents 30 - 50% of NTDs

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27
Q

What is a problem with fortifying our food supply with folic acid?

A

main issue is that if a pt has Vit B12 deficiency, the folate they are taking will mask the symptoms (hematologic disease) & will worsen the neurological symptoms

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28
Q

What are 3 classes of teratogens affecting neuronal development?

A

infectious agents
physical agents/temp
drugs

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29
Q

What are some of the infectious agent teratogens? What are their effects?

A

rubella-eye & ear defects
cytomegalovirus-eye defect, microcephaly
toxoplasmosis-hydrocephalus

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30
Q

Where do you find taxoplasmosis?

A

you find it in cat litter

it is a parasite

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31
Q

What are some physical agents that are teratogens? What are their effects?

A

X-rays–spina bifida occulta

hyperthermia–NTD

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32
Q

What are some drugs that are teratogens? What are their effects?

A

Epilepsy meds-NTD
Vit A overdose/acne meds-NTD
folic acid antagonists-NTD
alcohol-MR

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33
Q

There is a risk of which malformation of the fetus during weeks 0-3 in utero?

A

death of embryo may occur

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34
Q

There is a risk of which malformation of the fetus during weeks 3-8 in utero? What happens during this time frame?

A

risk of malformation of the embryo-esp heart defects

**maximally sensitive during this period

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35
Q

There is a risk of which malformation of the fetus during weeks 8-birth in utero? What happens during this time frame?

A

functional disturbance of the fetus, such as MR

during this time get growth & maturation of organ systems

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36
Q

What are some of the signs of FAS?

A 
thin upper lip
short palpebral fissure
flat nasal bridge
short nose
elongated philtrum
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37
Q

Describe the development of the placode & neural tube from the eye.

A

optic grooves form and then become optic vesicles.
overlying ectoderm becomes a lens placode
they both end up invaginating

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38
Q

The optic cup is connected to which structure?

A

optic stalk

39
Q

The lumen of the optic stalk leads to which space?

A

intraretinal space

40
Q

Which artery goes toward the lens placode?

A

hyaloid artery

41
Q

If you took a cross section of the optic stalk what would it show?

A

an outer layer & inner layer with a lumen in b/w
a hyaloid artery deep to the inner layer
and a choroid fissure that separates the 2 sides from making a tube

42
Q

If this choroid fissure remains…what happens? How common is this disease?

A

you get MAC disease
microphthalmia, anophthalmia, coloboma
***1/10000

43
Q

Describe the components of the eye in 7 week embryo.

A

the globe is in undifferentiated mesenchyme
ectoderm is on the outer surface
optic nerve fibers enter with a hyaloid vessel
there are also lens fibers & an anterior lens epithelium
there is an inner neural layer & an outer pigment layer of the retina

44
Q

What all happens with retinal detachment?

A

the inner layer of the retina peels off

45
Q

Describe the beginning steps of the formation of the inner ear.

A

Otic placode formed from ectoderm
the placode invaginates
it makes an otic pit
it makes an otic vesicle

46
Q

What happens to the epithelium in the otic vesicle?

A

it forms the statoacoustic ganglion (this lies next to the vesicle)

47
Q

What are the 2 sources of the tissue that composes the statoacoustic ganglion?

A

most comes from the otic placode
other parts come from neural crest cells
**none comes from neural tube

48
Q

Past the part that we have discussed, describe the formation of the inner ear.

A

Endolymphatic sac connects to endolymphatic duct
utricular portion of otic vesicle
goes to utriculosaccular duct
goes to saccular portion of otic vesicle
**then a tubular outgrowth of saccule happens & makes a swirl & forms the cochlear duct

49
Q

Describe the development of the canal of the inner ear.

A

you get flattened out pocketing of the utricle
get apposition of walls of opposing outpocketings
walls disappear & you get semicircular canals

50
Q

What is the middle ear derived from?

A

endoderm-tympanic cavity

1st & 2nd pharyngeal arches–ossicles

51
Q

Which types of genes regulate segmentation of the neuraxis?

A

Hox Genes

52
Q

T/F Hox genes are expressed in certain segments. If you misexpress them, you can change their fate.

A

True.

53
Q

Describe neural tube & ventricular development.

A

the lateral ventricles are significantly altered, but not the third ventricle
**Prosencephalon–>Telencephalon + Diencephalon
Mesencephalon remains.
Rhombencephalon–>Metencephalon + Myelencephalon
Spinal cord remains.

54
Q

If you peel away the cerebellum what are you left with?

A

a rhombus! Why it is called the rhombencephalon

55
Q

If you get a stenosis of the cerebral aqueduct, what condition do you develop?

A

hydrocephalus

56
Q

What are the 2 embryonic origins of the pituitary gland?

A

anterior lobe: ectoderm

posterior lobe: neural tube

57
Q

T/F Rathke’s pouch extends into the area of the diencephalon.

A

True. Note: rathke’s pouch gives rise to the adenohypophysis

58
Q

Where is a safe place to do a lumbar puncture?

A

L3/L4 you won’t hit spinal cord

59
Q

Describe spinal cord/vertebrae development.

A

at first the spinal cord grows much faster than the vertebrae
3 months in utero: have more spinal cord
but the vertebrae eventually catch up & outgrow in length

60
Q

What are the sources of neurons & glia?

A

neural tube (ventricular zone)
placodes
neural crest
stem cells

61
Q

Describe the process of neurogenesis in a ventricular zone.

A

cell’s axons extend from the ventricular zone to the marginal zone.
the cell body starts on one side & then becomes closer to the marginal side & then moves back down again. Then it loses its processes that contact the zones. It divides into 2 daughter cells. Then the daughter cell gets a process to each zone. This cycles until there are sufficient glioblasts

62
Q

Describe neural crest migration.

A

the upper portion of the tube has neural crest cells
these migrate along different pathways & attain different fates
they become mesenchymal cells, b/c this is what you must be to migrate.

63
Q

What are some of the different things that neural crest cells can become?

A 
pigment cells in skin
DRG or sympathetic ganglion
adrenal gland
some sort of plexus
chromaffin cells in adrenal medulla
multipolar neuron
schwann cell
satellite cell
64
Q

T/F Neural crest cells have a huge role in forming the back.

A

False. The face.

65
Q

The neural crest cells of the trunk crest makes spinal ganglia, and the cranial crest makes what?

A

cranial ganglia (5, 7, 9, 10)

66
Q

The neural crest cells of the cranial crest makes parasympathetic ganglia, but the trunk crest makes what?

A

sympathetic ganglia

67
Q

The neural crest cells of the trunk crest makes glial cells of peripheral nerves, but the cranial crest makes what?

A

glial cells of peripheral nerves & leptomeninges

68
Q

T/F Both neural crest cells of the trunk crest & cranial crest make melanocytes.

A

True.

69
Q

T/F Neural crest cells of the cranial chest make the adrenal medulla.

A

False. Of the trunk crest

70
Q

What are some other structures that neural crest cells of the cranial crest form?

A 
carotid body
thyroid
skeleton (cranial bone & cartilage)
CT (dermis, odontoblasts)
Muscle (ciliary & vascular)
71
Q

What is an embryonic stem cell?

A
  • self-renewing; can give rise to ALL tissue and cell types (including germ cells)
72
Q

What is a somatic stem cell?

A
  • Self-renewing

- Can give rise to full range of diploid, tissue-specific cell classes

73
Q

What is a neural stem cell?

A
  • self-renewing

- can give rise to any diploid cell type in the CNS or PNS

74
Q

What is a neural progenitor cell?

A
  • no self-renewal; can give rise to only one class of neurons
75
Q

What type of cells are microglia made from?

A

a type of mesenchymal cell that migrates into the brain

76
Q

How can you make a multipolar neuroblast?

A

a neuroepithelial cell–>
bipolar neuroblast–>
multipolar neuroblast

77
Q

How do you get a protoplasmic astrocyte?

A

a neuroepithelial cell–>
gliablast–>
protoplasmic astrocyte

78
Q

How do you get a fibrillar astrocyte?

A

a neuroepithelial cell–>
gliablast–>
fibrillar astrocyte

79
Q

How do you get oligodendroglia?

A

a neuroepithelial cell–>
gliablast–>
olgodendroglia

80
Q

How do you get an ependymal cell?

A

from a neuroepithelial cell

81
Q

Schwann cells myelinate axons located where?

A

located in the periphery

82
Q

Which type of cell myelinates axons in the CNS? Note: one of these cells myelinates a bunch of axons.

A

oligodendrocytes

83
Q

What are the 2 theories of how we get cellular diversity?

A

Lineage Theory & Environment Theory

84
Q

Describe the theory of cell lineage for cellular diversity.

A

an uncommitted precursor cleaves
second cleavage produces diversity of daughter cells
lineage leads to diversity in daughter cells
**cells acquire diverse fates at the precursor state
rely on information intrinsic to the cell

85
Q

Describe the theory of environment for cellular diversity.

A

uncommitted precursor
cleaves to form uncommitted daughter exposed to environmental signals, intercellular signals
signaling leads to diversity in daughter cells
**pleuropotential precursor, diversity generated among daughter cells from specific signals from other cells

86
Q

T/F Different signalling molecules turn neural crest progenitors into different phenotypes. Ex: Neural crest progenitor–>melanocyte via stem cell factor

A

True.

87
Q

Which factors allow you to go from neural crest progenitor to chromaffin cell?

A

glucocorticoids!

88
Q

Which factors allow you to go from neural crest progenitor to sensory neuron?

A

LIF: leukocyte initiating factor

89
Q

Which factors allow you to go from neural crest progenitor cell to adrenergic or cholinergic neurons?

A

Neural crest–>sympathetic progenitor via FGF2
Sympathetic Progenitor–>Adrenergic Neuron via NGF
Sympathetic Progenitor–>Cholinergic Neuron via Ciliary Neurotrophic Factor

90
Q

How do you generate a cortex?

A

by moving neurons from the ventricular zone to the cortex (plial surface) via radial glial processes

91
Q

Describe the inside out layer of the cortex.

A

studies have shown thru radioactive data
earliest neurons born are in the white matter
latest neurons born are in the cortex

92
Q

Should you get a 4 hour 4D ultrasound for your baby?

A

NO

93
Q

Give some examples of neuronal migration.

A

Neural Crest
Mesencephalic nucleus of the trigeminal nerve
Olfactory placode/hypothalamus: GnRH neurons
Oculomotor neurons: exchange across the midline

Block 5; Week 4 (10 decks)

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