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Embryo Exam 3 > T3 Neural Crest and Eye > Flashcards

T3 Neural Crest and Eye Flashcards

1
Q

Neural crest cells originate from where of the neural plate?

A

lateral margins

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2
Q

Neural crest cells are initially epithelial in nature and then transform into what and why?

A

mesenchymal cells; migratory purposes

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3
Q

The induction of neural crest tissue from non-neural ectoderm uses what? while induction from mesoderm uses what?

A

BMPs and Wnt; FGF8

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4
Q

What kind of cells are neural crest cells while they are in the neural tube?

A

epithelial cells

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5
Q

While neural crest cells are epithelial cells, cadherins and CAMs for what?

A

tight junctions

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6
Q

What are the factors that allow neural crest cells to break free of the CAMs and migrate?

A

Snail1, snail2, and Foxd3.

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7
Q

The first emigrating cells from the neural crest migrate by what pathway?

A

ventral/sympathoadrenal path. First to emerge as neural crest cells.

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8
Q

The second wave of emigrating cells from the neural crest migrate by what pathway?

A

ventrolateral path

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9
Q

The last wave of emigrating cells from the neural crest migrate by what pathway?

A

dorsolateral path

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10
Q

What neural crest cell migration wave has the most potential for differentiation?

A

early migratory neural crest cells

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11
Q

What neural crest cell migration wave can only differentiate into cells characteristic of more dorsal locations and form spinal ganglia?

A

later migratory neural crest cells

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12
Q

What neural crest cell migration wave can only form melanoblasts?

A

late migratory neural crest cells.

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13
Q

What are the three migratory pathway substrates that are important?

A

basal limina is preferable, extracellular matrix components (fibronectin, laminin, type 4 collagen), and ligand/receptor pair guidance molecules (robo/slit, ephrin/eph)

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14
Q

What are the divisions of neural crest cells?

A
  • trunk NC (derived from sympathoadrenal, sensory, and melanocyte lineages)
  • cranial NC
  • circumpharyngeal NC
  • cardiac NC
  • vagal crest
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15
Q

Where does trunk NC extend from?

A

somite 6, caudally

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16
Q

In the trunk NC, the sympathoadrenal path follows what?

A

intersomitic blood vessels around and between somites.

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17
Q

In the trunk NC, the ventrolateral path do what?

A

enter and pass through the anterior sclerotome compartments.

  • repulsed from posterior compartment by interaction of semaphorinA3F and Neurapilin2.
  • passage is facilitated via thrombospondin
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18
Q

In the trunk NC, the dorsolateral path cells migrate where?

A

just beneath the ectoderm

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19
Q

Cells from the sympathoadrenal lineage give rise to what?

A

adrenal chromaffin cells, adrenergic sympathetic neurons, and cholinergic sympathetic neurons

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20
Q

Cells from the sensory lineage give rise to what?

A

dorsal root ganglia and schwann cells

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21
Q

Cells from the melanocyte lineage give rise to what?

A

melanocytes

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22
Q

Cranial neural crest cells arise from what regions of prosomeres and migrate as a continuous sheet over much of the head?

A

1-3

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23
Q

What inhibits neural crest cells from arising anterior to diencephalon?

A

dickkopf-1

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24
Q

Do cells arising from diencephalon posteriorly through R3 express hox genes?

A

no

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25
Q

Cells arising from _____ and ________ do express hox genes?

A

R4; posteriorly

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26
Q

Neural crest cells from R1-2 migrate where, and do not require hox influence?

A

pharyngeal arch 1

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27
Q

Neural crest cells from R4 migrate where, and require hoxa2 to keep it from becoming the first arch?

A

pharyngeal arch 2

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28
Q

Neural crest cells from R6 and R7 migrate where, and do require hox3 influence?

A

pharyngeal arch 3

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29
Q

Neural crest cells from R1-2 migrate to what location?

A

pharyngeal arch 1

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30
Q

Neural crest cells from R4 migrate to what location?

A

pharyngeal arch 2

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31
Q

Neural crest cells from R6 and R7 migrate to what location?

A

pharyngeal arch 3

32
Q

From where does the circumpharyngeal neural crest arise?

A

from the area of somites 1-7

33
Q

Circumpharyngeal ridge is an arc-shaped aggregation of cells passing behind what pharyngeal arch?

34
Q

cells of the circumpharyngeal ridge migrate how to provide a pathway for CN XII and related musculature?

A

ventrally and then cranially

35
Q

Most neural crest cells of the circumpharyngeal lineage are from what somites?

36
Q

Most neural crest cells of the circumpharyngeal lineage pass into what pharyngeal arches or form what?

A

4 and 6; cardiac crest.

37
Q

What makes up the vagal crest?

A

neural crest cells from somite levels 1-3 + 4-7.

38
Q

Neural crest cells from somite levels 1-3 + 4-7 / vagal crest form what for digestive tract?

A

Parasympathetic innervation

39
Q

Cardiac neural crest arises from what somites?

A

somites 1-3.

40
Q

Where do the cardiac NC cells migrate?

A

toward the heart

41
Q

What do the cardiac NC cells give rise to?

A

-septa that divide conus arteriosus into aortic and pulmonary arteries
-leaflets of semilunar valves
thymus, thyroid, parathyroid glands

42
Q

What is expressed in the mesentery near the gut, and prevents neurons from crossing the midline of the CNS?

43
Q

Trunk neural crest cells express what, and avoid cells that express slit2?

A

Robo (slit receptor)

44
Q

Vagal crest cells do not express what and can therefore cross the gut wall?

45
Q

What role do slit2 and robo play?

A

answer later

46
Q

Where do the vagal neural crest cells arise from? What level of somites do they exit from?

A

circumpharyngeal crest, and exits from levels of somites 1-7

47
Q

vagal neural crest cells are mostly associated with what?

A

gut enteric system (parasympathetic)

48
Q

What is Waardenburg’s syndrome? What is it due to?

A
  • due to pax 3 mutations
  • involves pigmentation defects (white stripe in the hair), deafness, cleft palate, ocular hypertelorism, and sometimes hypoplasia of limb muscles.
49
Q

What does CHARGE (in regards to CHARGE syndrome) refer to?

A 
Coloboma
Heart disease
Atresia of nasal choanae
Retardation of development
Genital hypoplasia in males
Ear anomalies
50
Q

What is the inheritance pattern of CHARGE?

A

autosomal dominant, caused by mutation of the CHD7 gene on chromosome 8

51
Q

What is the mechanism for CHARGE syndrome?

A

suggested mechanisms are

  1. deficiency in migration of cervical neural crest cells into the derivatives of the pharyngeal pouches and arches
  2. deficiency of mesoderm formation
  3. defective interaction between neural crest cells and mesoderm, resulting in defects of blastogenesis
52
Q

What is DiGeorge syndrome? What is the mutation?

A
  • due to a deletion in chromosome 22
  • hypoplasia, reduced thymus, thyroid, and parathyroid function
  • cardiovascular defect including persistent truncus arteriosus
  • related to defects in neural crest assocated with 3rd and 4th pharyngeal arches
  • now referred to as Q22
53
Q

neurofibromas

A

need answer - from book

54
Q

What are ectodermal placodes?

A

local thickening in the embryonic ectodermal layer that generally constitutes a primordial group of cells from which a sense organ or ganglion will develop.

55
Q

What are the major placodes?

A
  • hypopheseal
  • olfactory
  • lens
  • trigeminal
  • optic
  • epibranchial
56
Q

What encircles the cranial plate, is induced by cranial mesoderm (+ neural tube), and involved activation of FGF pathways and inhibition of wnt and BMP?

A

preplacodal region

57
Q

The optic stalk is a lateral evagination of ______ which enlarges distally to form the optic vesicle.

A

diencephalon

58
Q

Does the optic vesicle invaginate symmetrically or asymmetrically?

A

asymmetrically.

59
Q

The groove of the optic stalk is continuous with what chamber of the eye?

60
Q

What artery uses the choroid fissure and optic stalk to pass into the posterior chamber of the eye?

A

hyaloid artery

61
Q

Where is Pax6 initially expressed?

A

lens, nasal placodes, and diencephalon

62
Q

What is the function of Pax6 in drosophila?

A

turns of gene sequence needed for eye development/master gene for eye development`

63
Q

What is the result of absence of Pax6 in mammals?

A

Absence of gene results in early optic vesicle formation, but the rest of the eye formation does not occur.

64
Q

High concentrations of what inhibits the expression of pax 6? What is expressed instead?

65
Q

Low concentrations of shh in distal optic stalk permit the expression of what, which leads to the development of the optic vesicle?

66
Q

What is the function of pax2

A

expression provides guidance of axons of ganglion cells from retina

67
Q

Lens nucleus is formed by lens fibers derived from where?

A

inner pole of lens vesicle

68
Q

Are lens fiber cells mitotic or postmitotic?

A

postmitotic

69
Q

What accumulates in the vitreous humor and stimulates formation of lens fibers?

A

retinal secretions, esp FGF

70
Q

What TF is necessary for corneal induction?

71
Q

What is the role of neural crest cells? TGFB? semaphorin 3a? neuropilin1? and hyaluronic acid?

72
Q

What forms the pigmented and the neural retina?

A

invaginated optic cup

73
Q

What is the outer thin layer of the optic cup after invagination occurs?

A

the pigmented retina

74
Q 
What, stimulated by shh, is necessary for the differentiation of the pigmented retina?
A. Pax6
B. Pax2
C. Otx2
D. FGF-8
75
Q

In regards to retinal polarity, which axis is fixed first?
A. Nasotemporal (anterior-posterior)
B. Dorsoventral
C. Cranial-caudal

A

Nasotemporal (anterior-posterior)

76
Q

In regards to retinal polarity, which axis is fixed second?
A. Nasotemporal (anterior-posterior)
B. Dorsoventral
C. Cranial-caudal

A

Dorsoventral

Embryo Exam 3 (8 decks)

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