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Block 5; Week 4 > Development-vonBartheld > Flashcards

Flashcards in Development-vonBartheld Deck (93):
1

What is the sequence of neural development?

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

2

How do you get the 3 germ layers developmentally?

epiblast cells invaginate thru the primitive streak.
Then you get ectoderm, mesoderm, and endoderm

3

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

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.

4

What induces the ectoderm to become a neural plate?

this induction happens via the notochord underneath the ectoderm.

5

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.

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

6

What does an organizer usu do in an amphibian?

generates axial mesoderm during normal development.

7

Who dated Hans Spemann?

von Bartheld's grandfather's sister. : )

8

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

Default: become neuronal
BMP4 inhibits this.

9

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

True.

10

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

True.

11

Where are neurons generated developmentally?

they are generated in the ventricular zone
the ventricular zone is made of the neuroepithelial layer that borders the neural tube.

12

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

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.

13

What is spina bifida occulta?

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

14

What is a meningocele?

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.

15

What is a meningomyocele?

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

16

What is rachischisis (no fold & fold)?

this is where you have no neural tube
the neural tissue that is overlying can be folded or not

17

What is a clinical sign of spina bifida occulta?

tufts of hair on lower back

18

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

cranial meningomyelocele
anencephaly

19

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

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

20

What is the most common human malformation?

neural tube defects

21

What is the incidence of NTDs?

1-8/1000 live births
**incidence has been more recently reduced b/c of abortions after detection of NTD

22

What is the etiology of NTD?

failure of the neural tube to close

23

What is the cause of NTD?

multifactorial
could be chromosomal, diabetes, teratogens, hyperthermia

24

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

epilepsy meds
acne meds (Vit A high)

25

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

ultrasound (detects anencephaly especially)
alpha fetoprotein

26

What is something that helps in prevents of NTDs?

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

27

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

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

28

What are 3 classes of teratogens affecting neuronal development?

infectious agents
physical agents/temp
drugs

29

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

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

30

Where do you find taxoplasmosis?

you find it in cat litter
it is a parasite

31

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

X-rays--spina bifida occulta
hyperthermia--NTD

32

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

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

33

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

death of embryo may occur

34

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

risk of malformation of the embryo-esp heart defects
**maximally sensitive during this period

35

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

functional disturbance of the fetus, such as MR
during this time get growth & maturation of organ systems

36

What are some of the signs of FAS?

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

37

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

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

38

The optic cup is connected to which structure?

optic stalk

39

The lumen of the optic stalk leads to which space?

intraretinal space

40

Which artery goes toward the lens placode?

hyaloid artery

41

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

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

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

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

43

Describe the components of the eye in 7 week embryo.

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

What all happens with retinal detachment?

the inner layer of the retina peels off

45

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

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

46

What happens to the epithelium in the otic vesicle?

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

47

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

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

48

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

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

Describe the development of the canal of the inner ear.

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

50

What is the middle ear derived from?

endoderm-tympanic cavity
1st & 2nd pharyngeal arches--ossicles

51

Which types of genes regulate segmentation of the neuraxis?

Hox Genes

52

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

True.

53

Describe neural tube & ventricular development.

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

54

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

a rhombus! Why it is called the rhombencephalon

55

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

hydrocephalus

56

What are the 2 embryonic origins of the pituitary gland?

anterior lobe: ectoderm
posterior lobe: neural tube

57

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

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

58

Where is a safe place to do a lumbar puncture?

L3/L4 you won't hit spinal cord

59

Describe spinal cord/vertebrae development.

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

What are the sources of neurons & glia?

neural tube (ventricular zone)
placodes
neural crest
stem cells

61

Describe the process of neurogenesis in a ventricular zone.

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

Describe neural crest migration.

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

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

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

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

False. The face.

65

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

cranial ganglia (5, 7, 9, 10)

66

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

sympathetic ganglia

67

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

glial cells of peripheral nerves & leptomeninges

68

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

True.

69

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

False. Of the trunk crest

70

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

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

71

What is an embryonic stem cell?

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

72

What is a somatic stem cell?

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

73

What is a neural stem cell?

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

74

What is a neural progenitor cell?

- no self-renewal; can give rise to only one class of neurons

75

What type of cells are microglia made from?

a type of mesenchymal cell that migrates into the brain

76

How can you make a multipolar neuroblast?

a neuroepithelial cell-->
bipolar neuroblast-->
multipolar neuroblast

77

How do you get a protoplasmic astrocyte?

a neuroepithelial cell-->
gliablast-->
protoplasmic astrocyte

78

How do you get a fibrillar astrocyte?

a neuroepithelial cell-->
gliablast-->
fibrillar astrocyte

79

How do you get oligodendroglia?

a neuroepithelial cell-->
gliablast-->
olgodendroglia

80

How do you get an ependymal cell?

from a neuroepithelial cell

81

Schwann cells myelinate axons located where?

located in the periphery

82

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

oligodendrocytes

83

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

Lineage Theory & Environment Theory

84

Describe the theory of cell lineage for cellular diversity.

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

Describe the theory of environment for cellular diversity.

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

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

True.

87

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

glucocorticoids!

88

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

LIF: leukocyte initiating factor

89

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

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

90

How do you generate a cortex?

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

91

Describe the inside out layer of the cortex.

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

92

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

NO

93

Give some examples of neuronal migration.

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