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Embryology > Lecture 3 > Flashcards

Lecture 3 Flashcards

1
Q

the embryo is a trilaminar germ disc at the beginning of wk ______.

A

4

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2
Q

Day 22 the embryo begins to:

A

fold.

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3
Q

By days 26/28, fold is complete and the embryo has _________ and is enclosed in:

A

intraembryonic coelom

amniotic sac

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4
Q

What beings dorsal to the notochord at day 22?

A

neurulation

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5
Q

which neuropore closes first?

A

cranial

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6
Q

Which neuropore closes second? what disappears after this?

A

caudal

the primitive streak disappears

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7
Q

What surrounds the neural tube and notochord by days 26/28?

A

sclerotome cells

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8
Q

When does the uteroplacental circulation begin to develop? describe how.

A

day 11-13

cytotrophoblasts bud into the syncytiotrophoblasts

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9
Q

What constitutes the formation of secondary stem villus? when does this happen?

A

day 16

extraembryonic mesoderm begins to proliferate and invade the center of primary stem villus

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10
Q

What constitutes the formation of tertiary stem villus? when does this happen? What’s the result?

A

day 21

the mesodermal core of secondary stem villus diff. into connective tissue and blood vessels

gases, nutrients, and wastes diffuse btwn maternal and fetal blood

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11
Q

What four tissues must the things that pass btwn maternal and fetal blood?

A
  • endothelium of villus capaillaries
  • extraembryonic mesoderm
  • cytotrophoblasts
  • syncytiotrophoblasts
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12
Q

What morphogen concentrations would we see in the ectoderm that will become the fore/midbrain on days 17-19?

A

increased FGF and decreased BMP

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13
Q

What morphogen concentrations would we see in the ectoderm that will become the hindbrain and spinal cord on days 17-19?

A

increased FGF and WNT

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14
Q

Neurulation takes place btwn what days?

A

17 and 30

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15
Q

What are the four steps of neurulation?

A
  1. neural plate forms neural groove
  2. hinge points are formed and facilitate the movement of cells
  3. neural crest cells guide endoderm cells at top of neural fold
  4. neural crest cells are ejected and remain outside of closed neural tube
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16
Q

In neurulation, what produces BMP? Noggin? SHH?

A

BMP: surface ectoderm
Noggin: dorsal neural folds
SHH: notochord and floor plate

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17
Q

In neurulation, why is Noggin necessary?

A

Noggin inhibits BMP (which inhibits DLHP)

DLHPs facilitate folding of neural tube so this allows process to continue correctly

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18
Q

In neurulation, why is SHH necessary?

A

prevents premature and unusual hinges from forming in neural plate

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19
Q

BMP forces surface ectoderm to differentiate into ->

A

skin cells

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20
Q

Neural plate is induced in what direction?

A

cranial-to-caudal

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21
Q

What is also happening while neural plate is induced cranially?

A

primitive streak and gastrulation continue caudally

22
Q

When is gastrulation finally finished? what day?

A

when the neural tube is formed and closed (closure of cranial and caudal neuropores) - day 28.

23
Q

When do neural folds first elevate and close?

A

5th somite (neck region)

24
Q

what day is the neural tube formed?

A

day 22

25
Q

once neural tube begins to close how does it proceed?

A

caudal and cranial directions (like a zipper)

26
Q

How many closure points are there on the neural tube?

A

5

27
Q

Where is the 2nd neural tube closure point and how does it proceed?

A

in front of the forebrain

proceeds caudally toward zipper advancing cranially

28
Q

When do the neuropores close respectively?

A

cranial -> day 25

caudal -> day 28

29
Q

Lack of closure of the neural tube leads to what kind of birth defect?

A

neural tube defects

30
Q

Anencephaly results from the failed closure of which neural tube site?

A

2

31
Q

Spina bifida results from the failed closure of which neural tube site?

A

5

32
Q

What cells are leftover from the neural tube closing (assist in moving folds)? What week do they arise?

A

neural crest cells

4th

33
Q

What do neural crest cells do after the neural tube is formed?

A

they migrate

34
Q

What do the first wave of neural crest cells become?

A

glandular cells

35
Q

What do the 2nd wave of neural crest cells become?

A

blood vessels
peripheral nervous system
etc.

36
Q

What do the neural crest cells that don’t migrate become?

A

pigment cells

37
Q

What germ layer is repsonsible for neural crest cells?

A

ectoderm

38
Q

What is mesenchyme? What can it be derived from?

A

loose connective tissue

can come from mesoderm, neural crest, etc.

39
Q

What does the intermediate mesoderm become?

A

kidney and gonad

40
Q

Paraxial mesoderm gives rise to ->

A

the head

somites

41
Q

Lateral plate mesoderm gives rise to ->

A
  • circulatory system (splanchic)
  • body cavity, pelvis, limb bones (somatic)
  • extraembryonic
42
Q

When does body folding occur? What types of bolding folding occur?

A
  • 3rd-4th wk

- lateral and cranial-caudal

43
Q

What is the driving force of cranial-caudal folding?

A

rapid growth of CNS (neural tube and somites)

44
Q

On day 22, the developing forebrain grows cranially beyond the buccopharyngeal membrane which results in:

A

forming of the heart tube

45
Q

What organ buds also begin forming during body folding?

A

lung, liver, and pancreatic

46
Q

What myotomes give rise to the diaphragm?

A

C3, 4, and 5

47
Q

What is the outer layer of the pleura? What does it attach to?

A

parietal -> attaches to chest wall

48
Q

What is the inner layer of the pleura? What does it cover?

A

visceral -> covers lungs, blood vessels, nerves, and bronchi.

49
Q

What event separates the pleural and pericardial cavities?

A

the fusion of the pleuropericardial folds

50
Q

Where do the pleuropericardial folds form?

A

opposite each other on the lateral body wall

51
Q

All the layers of the pleural and pericardial arise from what type of mesoderm?

A

lateral plate mesoderm

52
Q

What supplement helps prevent NTDs?

A

folic acid

Embryology (8 decks)

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