LEC 15: Embryology IV - 08.27.14 Flashcards Preview

STRUCTURES - WEEK 2 > LEC 15: Embryology IV - 08.27.14 > Flashcards

Flashcards in LEC 15: Embryology IV - 08.27.14 Deck (30):
1

notochordal process

mesenchymal cells from primitive node migrate cranially in the midline to form notochordal process

2

How does the notochordal process grow

notochordal process grows cranially between endoderm and ectoderm until it reaches the prechordal plate

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3

Characteristics of the notochord

  • primary inductor of the embryo
  • defines cranial-caudal axis
  • formation of vertebral column
  • induces overlying ectoderm to form neural plate

 

4

What induces the neural plate

neural plate is induces by underlying notochord

  • thickened embryonic ectoderm
  • neurectoderm gives rise to CNS

 

5

neurulation

formation of the neural tube (induced by underlying notochord)

6

How does the neural tube form

  • neural groove (day 18) and neural folds fuse to form a neural tube
  • fusion begins cranially
  • neural tube pinches off from surface ectoderm

 

7

When does the neural tube close

  • anterior neuropore (day 24-25)
  • posterior neuropore (day 27)

 

8

Fate of the neural tube (forebrain)

cerebral hemispheres

9

Fate of the neural tube (embryonic midbrain)

Adult midbrain

10

Fate of the neural tube (hindbrain)

  • pons
  • cerebellum
  • medulla oblongata

 

11

Fate of the neural tube (not forebrain, midbrain, or hindbrain)

spinal cord

 

12

Neural Crest Cells

  • neuroectodermal cells at the crest of each neural fold detach as the neural tube separates from the surface ectoderm
  • neural crest cells migrate to each side of the neural tube

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13

What derives from neural crest cells

  • dorsal root ganglia
  • ganglia of autonomic nervous system
  • cranial nerves (V, VII, IX, X)
  • peripheral nerve sheaths
  • melanocytes
  • adrenal medulla
  • facial muscles and bones

 

14

embryonic mesoderm

  • mesenchyme from primitive streak and notochordal process migrates laterally and cranially 
    • becomes continous with the extraembryonic (splanchnic) mesoderm
  • eventually becomes embryonic (somatic) mesoderm

15

What does embryonic (somatic) mesoderm derive from

extraembryonic (splanchnic) mesoderm

  • mesenchyme from primitive streak and notochordal process migrates laterally and cranially
  • becomes continuous with extraembryonic (splanchnic) mesoderm

 

16

Where does cardiogenic mesoderm derive from

Cardiogenic mesoderm derives from embryonic mesoderm

17

embryonic mesoderm separates ectoderm and endoderm everywhere except

1. oropharyngeal membrane (prechordal plate) - mouth

2. cloacal membrane - anus

18

Somites

embryonic mesoderm on both sides of the notochord proliferates to form a longitudinal column of paraxial mesoderm

  • paraxial mesoderm divides into paired blocks of mesoderm (somites)
  • somites appear first cranially (end of week 3)
  • 42-44 pairs of somites by end of week 5

 

19

How many pairs of somites are eventually formed, and where are they formed initially

  • somites initially appear cranially at end of week 3
  • 42-44 pairs of somites by end of week 5

 

20

Somites give rise to...

  • axial skeleton (vertebral column, sternum, skull, ribs)
  • skeletal muscles
  • dermis

 

21

formation of embryonic body cavity

  • coelomic spaces form in lateral mesoderm and cardiogenic mesoderm
  • spaces coalesce into horseshoe-shaped intraembryonic coelom (body cavity)

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22

What does the embryonic coelom become

1. pericardial cavity (heart)

2. pleural cavity (lungs)

3. peritoneal cavity (abdominal organs)

 

 

23

fetal circulation (angiogenesis)

  • begins at start of week 3
  • begins in:
    • extraembryonic mesoderm
    • yolk sac
    • connecting stalk
    • chorion
  • primordial uteroplacental circulation begins in week 3

 

24

angioblasts

  • mesenchymal cells in yolk sac (angioblasts)
  • angioblasts aggregate to form blood islands

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25

Describe the formation of blood vessels from blood islands formed by angioblasts

  • small cavities appear within blood islands
  • angioblasts flatten to form endothelium of blood vessels
  • endothelial-lined cavities fuse to form vessels

 

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26

hemocytoblasts

blood cells initially formed from endothelial cells of angioblasts

27

What do heart and great vessels form from

heart and great vessels mesenchyme in cardiogenic area 

28

Heart tube

  • paired endocardial tubes form during week 3
  • endocardial tubes fuse to form heart tube
  • heart tube joins with vessels to form primitive cardiovascular system
  • heart begins to beat by end of week 3

 

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29

allantois

out-pouching of yolk sac into connecting stalk; associated with the development of the urinary bladder

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30

neural tube defects

result from failure of closure of neural tube

  • spina bifida (caudal neural tube doesn't close)
  • anencephaly (cranial neural tube doesn't close)