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Embryology > Chapter 4- Third Week of Development > Flashcards

Chapter 4- Third Week of Development Flashcards

1
Q

4 General Events in 3rd week

A
  • Trilaminar disc
  • Primitive streak
  • Notochord
  • Germ layer differentiation
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2
Q

4 Events of Gastrulation

A
  • 3 Germ layers
  • Embryonic orientation
  • Trilaminar disc
  • morphogenesis begins
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3
Q

Embryonic ectoderm forms…

A 
CNS
PNS
Epidermis
Eyes
Inner Ear
Neural crest cells
Connective tissue of head
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4
Q

Embryonic Mesoderm forms…

A

Muscles
Blood cells
Linings of blood vessels and body cavities
Cardiovascular system
Organs of respiratory and excretory systems
Connective tissue (not head or limbs)

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5
Q

Embryonic Endoderm forms…

A

Epithelial linings of respiratory and alimentary systems

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6
Q

1st sign of gastrulation…

A

primitive streak

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7
Q

Cranial end of primitive streak

A

Primitive node

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8
Q

Primitive streak disappears by _________-

A

end of 4th week

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9
Q

Sacroccygeal teratoma

A

germ cell tumor that contains all 3 germ layers

female»males (80% of cases are in females)

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10
Q

Movement of primitive streak

A

caudal–>cranial

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11
Q

Cloacal membrane

A

future site of anus

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12
Q

Notochord

A
  • forms via Shh signaling
  • establishes the longitudinal axis
  • induces formation of neural plate
  • Aids in development of CNS and axial musculoskeletal system
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13
Q

Chordomas

A

Vestigal remnants of notochord tissues

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14
Q

Allantoic cyst

A

remnants of extraembryonic portions of allantois

may become inflamed in childhood/teens

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15
Q

Neurulation

A
  • Formation of neural plate, neural fold, and closure of neural folds to form neural tube
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16
Q

Neurulation ends at _____ with the ______

A
  • end of 4th week

- closure of the caudal neuropore

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17
Q

Neuroectoderm forms…

A 
CNS 
Brain
Spinal cord
Retina
Etc.
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18
Q

Neural plate invaginates and starts to form the neural tube at ________

A

~18 days

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19
Q

Neural Crest Cells form…

A
  • Sensory ganglia
  • Cranial Nerves V, VII, IX, and X
  • Pigment cells
  • Etc.
20
Q

Number of somites by days 26-32

A

38-39 pairs

21
Q

Number of somites by end of 5th week

A

42-44 pairs

22
Q

Intraembryonic coelom

A

body cavity- horseshoe shaped

23
Q

2 parts of mesoderm that form as a result of the intraembryonic coelom formation

A
  1. Somatic/parietal mesoderm

2. Splanchnic/visceral mesoderm

24
Q

Somatic/parietal mesoderm

A
  • Covers amnion

- Forms embryonic body wall

25
Somatopleure
embryonic body wall
26
Splanchnid/visceral mesoderm
- covers umbilical vesicle | - forms embryonic gut
27
Splanchnopleure
embryonic gut
28
Vasculogenesis
Formation of new vascular channel by assembly of angioblasts
29
Angiogenesis
Formation of new blood vessels through budding and branching off of pre-existing vessels
30
Blood cells develop from ______
hemangiogenic epithelium
31
Hematogenesis
blood formation
32
Hematogenesis begins _____
~5th week
33
Primordial heart tube forms from...
fusion of endocardial heart tubes
34
Heart beat starts around
22 days
35
Secondary chorionic villi
cover entire surface of chorionic sac
36
Tertiary chorionic villi
have blood vessels
37
Cytotrophoblastic shell
surround chorionic sac and attaches to endometrium
38
stem villi aka anchoring villi
attach to maternal tissue via the cytotrophoblastic shell
39
Branch villi
grow from sides of stem villi to allow for exchange
40
Hydatiform mole
placenta without development of tertiary villi | have cystic spaces that appear grapelike
41
Hydatiform mole characteristics
- various degrees of trophoblastic proliferation - high hCG levels - 3-5% develop into malignancy - can develop after spontaneous abortion or after normal fetal delivery
42
Choriocarcinomas
malignant trophoblastic lesions from hydatiform mole
43
2 types of complete hydatidiform moles
1. monospermatic mole | 2. dispermic mole
44
Monospermatic mole forms...
fertilization of an empty oocyte by 1 sperm that undergoes DNA replication
45
Dispermic mole forms..
fertilization of empty oocyte by 2 sperm
46
Partial hydatidiform mole forms
fertilization of a normal oocyte by 2 sperm
47
General summary of end of 3rd week of development
- bilaminar to trilaminar embryonic disc - gastrulation begins with primitive streak - oropharyngeal and cloacal membrane formed by end of 3rd week - notochord, neural crest cells, somites, and axial skeleton begin to form - Coelomic vesicle (body cavity precursor) forms - primordial heart forms - primary-->secondary-->tertiary chorionic villi form - cytotrophoblastic shell forms

Embryology (10 decks)

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