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LECOM MS1 Embryology > The Second Week (Exam 1) > Flashcards

The Second Week (Exam 1) Flashcards

1
Q

What are the rule of 2’s seen during the second week

A

2 embryonic layers each form 2 layers

2 cavities are formed

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2
Q

What are the two layers of cells that start the second week

A

Trophoblast

Embryoblast

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3
Q

What does the trophoblast give rise to

A

syncytiotrophoblast

cytotrophoblast

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4
Q

What does the embryoblast give rise to

A

hypoblast

epiblast

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5
Q

What is the syncytiotrophoblast

A

multinucleated blob that secretes hCG

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6
Q

What is the cytotrophoblast

A

invades the uterus, very cellular

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7
Q

What is the epiblast

A

primordial germ cells that will form all embryonic tissues

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8
Q

What two cavities form during the second week

A

amniotic cavity

yolk sac

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9
Q

What are the sources of amniotic fluid

A

mother: leaky capillary beds in the placenta

Fetus: Urine

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10
Q

What is polyhydraminos

A

too much amniotic fluid

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11
Q

What is oligohydraminos

A

too little amniotic fluid

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12
Q

What clinical problems may lead to polyhydraminos

A

swallowing defects, GI issue, digestive congenital anomaly

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13
Q

What clinical problems may lead to oligohydraminos

A

no external genitalia

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14
Q

What are the contents of the amniotic fluid

A 
fetal cells
alpha-fetoprotein
Acetylcholinesterase
pulmonary phospholipids/lamellar bodies
infections
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15
Q

What might high levels of alpha-fetoprotein indicate

A

body wall defect

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16
Q

What is the yolk sac formed from

A

hypoblast

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17
Q

Describe the lining of the primitive yolk sac

A

hypoblast that lines is now called extraembryonic endoderm

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18
Q

What is the entire lining of the yolk sac called

A

heuser’s membrane

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19
Q

Where is the extraembryonic reticulum secreted

A

between extraembryonic endoderm and the cytotrophoblast

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20
Q

What does the extraembryonic reticulum do

A

separate yolk sac and embryoblast from the trophoblast

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21
Q

What are the two layers of the extraembryonic mesoderm

A

Somatopleuric

Splanchnopleuric

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22
Q

What is the somatopleuric layer of the extraembryonic mesoderm in contact with

A

trophoblast

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23
Q

What is the splanchnopleuric layer of the extraembryonic mesoderm in contact with

A

embryo

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24
Q

What is the chorionic cavity surrounded by

A

extraembryonic mesoderm

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25
Q

What type of cells will be formed from extraembryonic mesoderm

A

primordial placenta cells as it is outside of the embryo

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26
Q

When is the yolk sac classified as secondary

A

when exocoelomic cyst splits off it is considered secondary

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27
Q

What will the syncytiotrophoblast do

A

invade uterus epithelium and secretes hCG

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28
Q

What will cytotrophast do

A

continue to proliferate

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29
Q

What is secreted by the cytotrophoblast

A

enzymes that break down ECM of endometrial cells

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30
Q

What subunit of hCG is unique

A

Beta subunit

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31
Q

When can beta hCG be detected

A

6-8 days after ovulation

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32
Q

What is negative beta hCG <5 mlU/mL

A

<5 mlU/mL

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33
Q

What is positive beta hCG

A

> 25mIU/mL

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34
Q

How many days does it take for hCG to double

A

every 2.2 days

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35
Q

How will hCG levels differ in patients who’s pregnancies are destined to abort

A

they decrease or do not develop as fast

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36
Q

When will there be increased levels of hCG

A 
molar pregnancies
pregnancy
choriocarcinoma
germ cell tumors
hepatoma
lymphoma
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37
Q

How will hCG be in ectopic pregnancies

A

lower range

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38
Q

Situations in which there would be a decreased level of hCG

A

indicative of decreased viability of the placenta

risk of spontaneous abortion dead fetus

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39
Q

What will happen within the trophoblast around day 9

A

uteroplacental circulation begins to form

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40
Q

What forms the start of uteroplacental circulation

A

spaces begin to form within the syncytiotrophoblast

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41
Q

What are the spaces of the syncytiotrophoblast at the start of uteroplacental circulation called

A

trophoblastic lacunae

42
Q

What occurs at the same time as trophoblastic lacunae formation

A

maternal capillaries near the syncytiotrophoblast begin to expand

43
Q

What are the expanded capillaries near the syncytiotrophoblast called

A

maternal sinusoids

44
Q

What do the maternal sinusoids do after being formed

A

join the trophoblastic lacunae (maternal blood fills the lacunae)

45
Q

When do primary stem villi form

A

between days 11-13

46
Q

What are primary stem villi

A

cytotrophoblast proliferates and forms extensions that extend into the syncytiotrophoblast that extend into the blood filled lacunae

47
Q

Primary stem villi are the first steps in forming what

A

fetal arteries and veins

48
Q

What are the layers of the primary stem villi

A

cytotrophoblast (inner)

syncytiotrophoblast (outside)

49
Q

When are secondary stem villi formed

A

day 16

50
Q

What are secondary stem villi

A

extraembryonic mesoderm extends into primary villi

51
Q

When are tertiary stem villi formed

A

End of the third week

52
Q

What is a tertiary stem villi

A

villus has formed new blood vessels that connect to forming fetal blood vessels

53
Q

What occurs on Day 6

A

implantation

54
Q

What occurs on Day 16

A

gastrulation

55
Q

What occurs on Day 18

A

neural plate forms

56
Q

What occurs on day 20

A

first somite forms

57
Q

What occurs on Day 22

A

neural tube begins to close and heart begins to beat

58
Q

What occurs on day 24

A

thyroid gland begins to form

59
Q

What occurs on Day 24-25

A

cranial neuropore closes

60
Q

What occurs on day 26-27

A

caudal neuropore closes

61
Q

What occurs on week 2

A

primordial germ cells arise from the epiblast

62
Q

What occurs on week 3

A

primordial germ cells in the yolk sac

63
Q

What occurs on Week 4

A

pharyngeal arches form

64
Q

What occurs on week 6

A

primordial germ cells arrive at genital ridge/ midgut herniation

65
Q

What occurs on week 9

A

external genitalia can be distinguished/ liver begins blood formation

66
Q

What occurs on week 10

A

return of midgut

67
Q

What occurs on week 12

A

blood formation involves spleen

68
Q

What occurs on week 30

A

blood formation shifts to marrow

69
Q

What is the embryonic part of the placenta

A

tertiary stem villi

70
Q

What is the function of the tertiary stem villi

A

route for exchange and diffusion

71
Q

What layers will INITIALLY need to be transversed in a tertiary villi for exchange between mother and fetus

A

cytotrophoblast
syncytiotrophoblast
CT/ECM of villus
Endothelium of embryonic vessels

72
Q

What layers will need to be transversed over time in a tertialry villi

A

the syncytiotrophoblast

73
Q

What occurs over time to the tertiary villi

A

fetal blood vessels get closer to wall of syncytiotrophoblast and cytotrophoblast is dispersed

74
Q

What is the chorion composed of

A

syncytiotrophoblast
cytotrophoblast
extraembryonic membrane

75
Q

What is the function of the chorion

A

help form placenta

76
Q

How do genomic imprinting of maternal and paternal genome affect blastocyst formation

A

Maternal genome plays a role in eMbryonic development

Pateral genome plays a role in troPhoblast development (Placental)

77
Q

What symptoms occur with hydatidiform mole

A 
high hCG
hypertension
bleeding
uterus enlargement greater than expected
theca lutein cysts
78
Q

What is hydatidiform mole

A

placenta without an embryo

79
Q

What are the two proposed mechanisms for molar pregnancy

A

fertilization of an empty occyte with duplication

fertilization of an oocyte by two sperms

80
Q

What is complete molar pregnancy

A

cystic swelling that arises from development of trophoblast without an embryoblast

81
Q

What is partial molar pregnancy

A

poorly developed embryo

82
Q

What genome does a partial molar pregnancy have

A

triploid (XXX or XXY)

83
Q

What causes partial molar pregnancy

A

2 sperm fertilized a normal ovum

84
Q

What type of cancer is associated with molar pregnancy

A

choriocarcinomas

85
Q

Where do choriocarcinomas often metastasize

A

to the lungs and requires chest scans

86
Q

What is a hydropic chorionic villi

A

fluid filled villi associated with molar pregnancy; no embryo to drain the spaces so fluid builds up

can be seen on US

87
Q

Key signs and symptoms of molar pregnancy

A 
bleeding
lower abdominal pain
pre-eclampsia before 24 weeks
uterus large for dates
absent fetal hear sounds, no fetal parts on US
Expulsion of "grape-like" vesicles
88
Q

What diagnostic studies are used in molar pregnancies

A

beta hCG (elevated)
US
Chest films: rule out choriocarcinomas

89
Q

When the blastocyst has a endoblast and hypoblast, what is the embryo referred to as

A

bilaminar germ disc

90
Q

The amniotic cavity forms

A

between the epiblast cells

91
Q

Where does the chorionic cavity form from

A

the extraembryonic mesoderm

92
Q

With the chorionic cavity, the extraembryonic mesoderm is divided into what

A

two layers:
splanchnopleuric
somatopleuric

93
Q

Where does the somatopleuric layer go

A

lines the cytotrophoblast

94
Q

What does the somatopleuric layer do

A

help form the chorion

95
Q

Where does the splanchnopleuric layer go

A

in contact with germ disk

96
Q

What does the splanchnopleuric layer contribute to

A

umbilical cord

97
Q

The chorion helps form what

A

the placenta

98
Q

What is the chorion composed of

A

somatopleuric layer of extraembryonic mesoderm
cytotrophoblast
syncytiotrophoblast

99
Q

90% of complete moles are what

A

46, XX

100
Q

In origin, what are complete moles genetically

A

paternal

101
Q

What percentage of moles go on to form choriocarcinomas

A

5%

102
Q

Where do choriocarcinomas metastasize to

A

brain, bone, and lungs

LECOM MS1 Embryology (19 decks)

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