Embryology: Folding and Body Cavities Flashcards Preview

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Flashcards in Embryology: Folding and Body Cavities Deck (47)
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1
Q

in the folding of the embryo, what three fold that happen at the sam time?

A

head, tail and transverse

2
Q

Before any folding occurs, what structure is most rostral?

A

septum transversum –> gives rise to Diaphragm

3
Q

Around what week does folding occur?

A

4th week

4
Q

As the neural tube moves forward, what begins to close?

A

rostral neuropore

5
Q

The notochord gets tucked ventrally and caudally, what now is the most rostral structure? most caudal?

A

from rostral - caudal:

intra-embryonic coelum –> heart tubes –> septum transversum

6
Q

Before folding, what three things sit in the prochordal mesoderm?

A

1) Septum transversum
2) Heart tube
3) Intra-embryonic coelum

7
Q

the membrane connecting the notochord with the prochordal mesoderm is?

A

oropharyngeal membrane

8
Q

What is the purpose of the oropharyngeal membrane?

A

acts as a “hinge” or pivot point and all structures will rotate around each other

9
Q

During this process a portion of yolk sac becomes engulfed as well and forms the?

A

foregut

10
Q

the remainder of the yolk sac that is not engulfed during folding goes?

A

it is squeezed out the ventral midline

11
Q

as the neural tube folds caudally, what moves?

A

the collecting stalk and alianois get shifted ventrally

12
Q

after the head fold, where is the oropharyngeal membrane located?

A

ventral to all structures ( heart tubes, IEC and septum transversum)

13
Q

what makes up the amniotic membrane?

A

EEM+Ectoderm

14
Q

What are the clinical significances of the head fold?

A

1) foregut formed
2) oropharyngeal membrane ventral toCNS
3) heart is ventral to CNS and gut
4) heart is dorsal to intraembryonic coelom
5) septum transversum is caudal to heart
6) rostral neuropore closes
7) ectoderm now covers rostral end of embryo while amniotic cavity surrounds the rostral end of embryo

15
Q

What are rostral neural tube defects?

A

anencephaly and exencephaly

16
Q

during the tail fold, the portion of the yolk sac that gets engulfed forms the?

A

hind gut

17
Q

the membrane connecting the notochord/neural tube with EEM is?

A

cloacal membrane

18
Q

the cloacal membrane will give rise to?

A

the anus

19
Q

the caudal portion of the hindgut that sticks out is called?

A

cloaca

20
Q

the cloaca will give rise to the?

A

rectum and urinary bladder

21
Q

What covers the caudal end of the embryo?

A

ectoderm

22
Q

What surrounds the caudal end of the embryo?

A

amniotic cavity

23
Q

consequences and clinical significance of the tail fold?

A

spina bifida and spinal dermal sinus

spinal dermal sinus- the epidermal cells end up proliferating in dura matter of spinal cord

24
Q

After the folds, EEM will complete surround the embryo except at one spot? where and what does it give rise to?

A

ventral to the midline

it will give rise to umbilical ring

25
Q

Before transverse folding, Mesoderm that is anterior to the IEC is called?

A

Somatic mesoderm

26
Q

Before transverse folding, Mesoderm that is posterior to IEC is called?

A

Splanchnic mesoderm

27
Q

What occurs during the lateral or transverse fold?

A

the body wall folds down on both sides to enclose the embryoonic cut and IEC

28
Q

The Somatic mesoderm swings down as ectoderm swings down and surrounds what structure?

A

mid gut

29
Q

What is a somatopleure?

A

somatic mesoderm of lateral plate + ECTOderm

30
Q

What is a spanchopleure?

A

splanchnic mesoderm of lateral plate + ENDOderm

31
Q

when mesenchymal cells (mesoderm) encouter a fluid filled space (like IEC)

A

epithelium, but since it is made of mesenchymal cells= mesothelium

32
Q

at the end of the transverse fold, the IEC surrounds what mesoderm?

A

splanchnic

33
Q

somatic mesoderm will give rise to?

A

PARIETAL, lining of body cavities

34
Q

splanchnic mesoderm will give rise to?

A

VISCERAL- outer layer of the organ

35
Q

Two fused layers of mesothelium is called?

A

Mesentery

36
Q

During the transverse fold, what is the IEC continuous with?

A

chronic cavity

37
Q

as the embryo starts to grow, the amniotic will expand and fuse with ?

A

amnion + chorion = amniochorionic membrane

38
Q

what is the umbilical ring?

A

where ectoderm meets amnion

39
Q

where do the umbilical vessels form?

A

in collecting stalk

40
Q

what vessels compose an umbilical cord?

A

2 arteries and 1 vein

41
Q

what are the contents and layers of the umbilius

A

1) many layers of EEM = collecting stalk
2) Allantois (located inside stalk)
3) umbilical BVs
4) yolk stalk (has its own layer of EEM)

42
Q

After transverse folding, what surrounds the yolk stalk?

A

IEC

43
Q

ectoderm and amniotic cavity cover the ventral embryo except at the?

A

umbilical ring

44
Q

definitive umbilicus has formed and is wrapped in?

A

amniotic membrane

45
Q

the transverse folding process gives rise to what structure?

A

midgut

46
Q

can the midgut still communicate outside the embryo?

A

yes, it connects with the residual yolk sac outside the embryo via yolk sac through vitelline duct

47
Q

What is gastroschisis?

A

means “split gut” - failure in the transverse folding process, allows contents of body cavities to communicate and herniate outside the embryo