Week 3- Formation of Germ Layers Flashcards

1
Q

which embryonic week is characterized by rapid development from the embryonic disc to the actual embryo?

A

week 3 of development

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2
Q

what three main things happen surfing week 3 of development

A
  • primitive streak appears
  • notochord develops
  • three germ layers separate
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3
Q

what are some frequent pregnancy symptoms

A
  • nausea

- vomiting

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4
Q

what does not rule out pregnancy because it could be caused by implantation bleeding?

A

vaginal bleeding

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5
Q

what results from the leakage of blood into the uterine cavity from disrupted lacunar networks in the implanted blastocyst?

A

implantation bleeding

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6
Q

what means the formation of the three germ layers

A

grastrualtion

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7
Q

what are the three different germ layers

A

ectoderm
mesoderm
endoderm

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8
Q

during grastrulation what happens to the bilaminar dic

A

it becomes a trilaminar dic

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9
Q

what is morphogenesis?

A

the development of the embryos’s body form

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10
Q

when is morphogenesis really significant?

A

during week 3 of development

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11
Q

what are the 3 signaling proteins that play an essential role in grastualtin?

A
  • BMP’s ( Bone Morphogenetic Proteins)
  • FGFs (Fibroblast Growth Factors)
  • Wnts
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12
Q

which germ layer gives rise to

  • epidermis
  • PNS
  • eye
  • inner ear
  • neural crest cells
A

ectoderm

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13
Q

which germ layer is the source of

  • epithelial linings of respiratory and digestive tracts
  • liver
  • pancreas
A

endoderm

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14
Q

which germ layer give rise to

  • skeletal system
  • connective tissue
  • dermis
  • blood cells
  • circulatory system
A

mesoderm

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15
Q

what appears caudally in the median plane of the dorsal aspect of the embryonic disc

A

the primitive streak

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16
Q

the cranial end of the primitive streak proliferates to form what

A

primitive node

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17
Q

what happens to primitive streak overtime

A

it diminishes in relative size and becomes an insignificant structre

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18
Q

when does the primitive streak usually disappear?

A

week 4

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19
Q

what is sacroccygela teratoma?

A

this is when there is a remnant of the primitive streak and a tumor that contains tissues from all three germ layers is present (hair and teeth)

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20
Q

which infants are most affected by sacroccygeal teratoma (80%)

A

females

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21
Q

you can see a sacrococcygeal teratoma with what device?

A

sonograph

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22
Q

the notochordal process is formed by cells that migrate through the streak when?

A

day 16 of embryonic development

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23
Q

what are considered to be benign and malignant tumors that may form from vestigial remnants of notochrdal tissues

A

chordomas

24
Q

1/3 of chordomas occur where

A

at the base of the cranium and extend to the nasopharynx

25
Q

at what rate dies a chroma grow

A

slowly

26
Q

at day 16 what appears as a small sausage that is outpouching from the caudal wall of the umbilical vesicle that extends to the connecting stalk?

A

allantois

27
Q

the proximal part of the alantois that remains through development is called the

A

urachus

28
Q

what extends from the bladder to the umbilical region

A

urachus

29
Q

what is the urachus represented by in adults

A

the median umbilical ligament

30
Q

what are known as the remnants of the extraembryonic potion of the allantois, and are usually found between the fetal umbilical vessels and can be detected by ultrasound

A

allantoic cyst

31
Q

allantoic cysts are generally asymptomatic till when

A

childhood or adolescence because thats when they start running around a lot more

32
Q

what is the process involved in the formation of the neural plate and neural folds and closure of the folds to form the neural tube

A

neurulation

33
Q

durring neuraltion what may the embryo be referred as?

A

a nerurula

34
Q

the notochord induces the embryonic ectoderm to do what adjacent to the midline

A

it induces it to thicken and form elongated plate of epithelial cells called the neural plate

35
Q

the ectoderm of the neural plate (neuroectoderm) gives rise to what

A

CNS

36
Q

the neural folds are prominent where

A

at the cranial end of the embryo

37
Q

the cranial neural folds indicate what kind of development

A

brain development

38
Q

when do the neural folds move together?

A

by the end of week 3

39
Q

when the neural folds move together at the end of week 3 the neural plate turns into the…?

A

nerual tube

40
Q

what ganglia of cranial nerve cells derive in part from the mesoderm

A

CN V, CN VII, CN IX, and CN X

41
Q

the disturbance of neurulation may cause some abnormalities where

A

in the brain and spinal cord

42
Q

meroencephaly

A

partial absence of the brain

43
Q

3 neural tube abnormalities

A
  • ancephaly
  • spina bifida
  • meroencephaly
44
Q

at the end of the 3rd week the paraxial mesoderm differentiates and divides into paired cuboidal bodies called?

A

somites

45
Q

by the end of the 5th week how many somites are there

A

42-44 pairs

46
Q

somites are the primordial for what

A

the skeletal system

47
Q

somites can help determine what

A

embryonic age (at 4- 5 weeks old)

48
Q

what does the somatic mesoderm and embryonic ectoderm form?

A

somatopleure, or embryonic body wall

49
Q

the splanchnic mesoderm and underlying embryonic endoderm for the embryonic gut also known as?

A

splanchopleure

50
Q

when will the intraembryonic coelm divide

A

by the end of the second month in three cavities

51
Q

what are the 3 cavities of the intraembryonic coelom

A
  • pericardial cavity
  • pleural cavities
  • peritoneal cavity
52
Q

vasculogenesis and angiogenesis takes place when

A

at the beginning of week 3

53
Q

what is the development of blood vessels called?

A

angiogensesis

54
Q

why does the cardiovascular system form so early

A

because there is an urgent need for blood vessels to bring oxygen

55
Q

what is the early embryo called when the nerual tube is developing (third to fourth week)?

A

Neurula