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REPRODUCTIVE SYSTEM > Fetal Development > Flashcards

Fetal Development Flashcards

1
Q

Lasts for 8 weeks, organogenesis takes place

A

Embryonic period

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2
Q

Chorionic sac 1cm
True intervillous space formed
Fetal BV in chorionic villi appear

A

3rd week after ovulation

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3
Q

Chorionic sac 2-3cm
Embryo 4-5cm
Arm and leg buds present

Formed: PUC
Primitive heart
Umbilical cord
Cardiovascular system

A

4th week

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4
Q

Embryo 22-24mm
Head larger than trunk
Finger toes present

Complete:
Heart
Upper lip

A

6th week

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5
Q

External ears form definitive elevations on either side of head

A

6th wk

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6
Q

Earliest synapses in the spinal cord develop

A

6th

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7
Q

Consist of growth and maturation of structures that were formed during the embryonic period

A

Fetal period

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8
Q

8 weeks after fertilization or 10 weeks after onset of last menses

A

Fetal period

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9
Q

Embryo-fetys is nearly

A

4 cm long

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10
Q

UCC

Uterus is palpable (above symphysis pubis)
Crown-rump length 6-7cm
Centers for ossification appear

A

12 weeks

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11
Q

Fingers toes have become differentiated

Skin and nails develop

A

12 weeks

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12
Q

External genitalia start to show definitive signs of gender

Fetus begin to make spontaneous movements

A

12th

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13
Q

CRL (crown rump length) 12cm

Weight: 110g

A

16th week

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14
Q

Eye movement begin at

A

16-18 weeks with midbrain maturation

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15
Q

Weight >300g
Fetal skin = less transparent

Downy lanugo covers entire body
Developed scalp hairs

A

20 weeks

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16
Q

Weight 630g
Skin is wrinkled
Fat deposition
Eyebrows and eyelashes recognize

A

24th week

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17
Q

Canalicular period of lung development

A

24th week

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18
Q

CRL: 25cm
Weight: 1,100g

Thin skin is red and covered w vernix caseosa
90% chance of survival

A

28 weeks

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19
Q

CRL: 28cm
Weight: 1,800g

A

32 weeks

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20
Q

CRL: 32cm
Weight: 2,500g

Body more rotund bcs of deposition of subcutaneous fat

A

36 weeks

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21
Q

CRL: 36cm
Weight: 3,400g

Fully developed

A

40 weeks

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22
Q

Thickened disk-shaped growing to a diameter of 20cm

A

Placenta

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23
Q

Fetal portion is derived from

A

Chorion

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24
Q

One of the surrounding extraembryonic membranes of conceptus

A

Chorion

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25
Q

Derived from the region of endometrium that underlies the implantation site (the deciduas basalis)

A

Maternal portion

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26
Q

Development of the placenta: the EARLY blastocyst consists of a single layer of

A

Ectoderm

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27
Q

What consists of an inner cell mass that gives rise to the embryo and outer, single layer of trophoblast cells that encloses the blastocyst cabity

A

Late blastocyst

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28
Q

Blastocyst implants high up on the

A

Posterior wall of uterus

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29
Q

Following implantation, these become highly invasive and erode the endometrium

A

Trophoblast cells

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30
Q

As the blastocyst buries itself in the endometrium, it is covered by both

A

Trophoblast and decidua (the endometrium of the preg uterus)

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31
Q

One pole of the buried blastocyst extends towards the endometrial cavity and is covered by

A

Chorion frondosum and deciduas capsularis

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32
Q

The innermost pole ultimately forms the

A

Placenta

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33
Q

Contiguous with maternal decidua (and later maternal blood)

A

Syncytiotrophoblast

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34
Q

Outer layer

A

Syncytiotrophoblast

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35
Q

Syncytiotrophoblast has no individual cells instead it had an

A

Amorphous cytoplasm

without cell borders, and nuclei that are multiple and diverse

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36
Q

Innermost layer (embryonic side)

A

Cytotrophoblast

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37
Q

Cells nearest the intervillous space; well-demarcated cell border and a single nucleus

A

Cytotrophoblast

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38
Q

After implantation is complete, trophoblast further differentiates into:

A
  • Villous trophoblasts
  • Extravillous trophoblasts
    • Interstitial
    • Endovascular
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39
Q

Give rise to chorionic villi which transport oxygen and nutrients between fetus and mother

A

Villous trophoblasts

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40
Q

Invades deciduas and penetrates myometrium to form placental bed giant cells

A

Interstitial trophoblasts

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41
Q

Surrounds spiral arteries and prepare these vessels for endovascular trophoblast invasion

A

Interstitial trophoblasts

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42
Q

Surrounds spiral arteries and prepare these vessels for endovascular trophoblast invasion

A

Interstitial trophoblasts

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43
Q

Penetrates lumen of spiral arteries by intially forming cellular plugs then destroying vascular endothelium via an apoptosis mechanism then invading vascular media

A

Endovascular trophoblasts

44
Q

Trophoblasts only invade

A

Spiral arteries

NOT VEINS

45
Q

Endovascular invasion proceeds into 2 waves/stages

A

First wave (BEFORE 12 WKS POSTFERTILIZATION)

Second wave (BETWEEN 12 AND 16 WEEKS)

46
Q

Consists of invasion and modification of spiral arteries up to the border between decidua and myometrium

A

First wave

47
Q

Involves invasion of intramyometrial segments of spiral arteries

A

Second wave

48
Q

Endovascular invasion of trophoblasts converts narrow-lumen muscular spiral into

A

Dilated, low resistance uteroplacental vessels (also important in pathogenesis of pre eclampsia and fetal growth restriction

49
Q

Invades most superficial portion of endometrium, spiral arteries and arterioles are invaded and destroyed

A

Cytotrophoblasts

50
Q

As endometrial invasion proceeds, maternal BV are trapped to form

A

Lacunae (lakes) - which soon fill w maternal bld

51
Q

Invades the endometrium and become surrounded by lacunae

A

Irregular protrusions of syncytiotrophoblast

52
Q

Finger-like extensions of the cytotrophoblast grow into these protrusions forming structures called

A

Primary placental villi

53
Q

Distinguished on about 12th day after fertilization

A

Chorionic villi

54
Q

When the solid trophoblastic column is invaded by a mesenchymal core, these are formed

A

Secondary villi

55
Q

After angiogenesis occurs in situ from mesenchymal core, the villi are

A

Tertiary

56
Q

Maternal arterial blood enters the intervillous space by day

A

14 or 15 postfertilization

57
Q

Fetal and maternal BV of the embryo are fxnal and placental circulation is est

A

By about 17th day

58
Q

The feto-placental circ is completed when BV of embryo are connected w the chorionic vessels wc are formed in situ from

A

cytotrophoblasts

59
Q

Chorionic plate

A

Roof of intervillous spaces

60
Q

Basal plate

A

Floor of intervillous spaces

61
Q

Are villi of the chorion frondosum extending from the chorionic plate to the deciduas

A

Anchoring villi

62
Q

most villi arbores and end freely in the

A

intervillous spaces

63
Q

supplied w a chorionic artery and vein

A

cotyledon

64
Q

consist of decidual tissue w trophoblasts and are of fetal and maternal origin

A

placental septa

65
Q

through the 2 umbilical arteries, then into the capillaries of the villi and finally back thru a single umbilical vein into the fetus

A

fetal blood flow

66
Q

branches of the umbilical vessels that traverses along the surface of the placenta

A

placental surface or chorionic vessels

67
Q

Chorionic ___ always cross over chorionic _____

A

Chorionic artery always cross over chorionic veins

68
Q

what are perforating branches of the surface arteries that pass thru the chorionic plate

A

truncal arteries

69
Q

placental circulation

A

intervillous spaces –> chorionic plate –> basal plate –> uterine veins –> placenta

70
Q

maternal blood enters intervillous spaces in spurts propelled by

A

maternal blood pressure

71
Q

this force blood in discrete streams towards the chorionic plate until the head of pressure is

A

reduced then lateral spread then occurs

72
Q

arterial bld exits basal plate and drains thru

A

uterine veins

73
Q

TO the uterine wall, what are the arteries and veins

A

arteries are perpendicular to uterine wall

veins are parallel to uterine wall

74
Q

6 components of placental barrier lying between the maternal and fetal circulations are:

A
  1. syncytiotrophoblasts
  2. cytotrophoblast
  3. trophoblastic basement membrane
  4. fetal loose CT
  5. endothelium of fetal capillaries
  6. its surrounding basement membrane
75
Q

at full term, the cytotrophoblast is represented only as

A

fragments (hence the placental barriers consists only 5 fetal compo)

76
Q

early months of pregnancy, placental mem is still

A

thick and not fully dev
therefore, permeability is low
surface area is slight

77
Q

later pregnancy

A

increase permeability
thinning mem
SA expands
increase placental diffusion

78
Q

dissolved O2 in bld of large maternal sinuses passes into fetal bld by

A

simple diffusion, driven by an O2 pressure gradient

79
Q

3 reasons why fetus is able to obtain sufficient O2 to maternal blood

A
  1. HbF carry more O2 (20-50%)
  2. Hb conc of fetal is 50% greater than mom’s (enhancing the amount of O2 transported to fetal tissues)
  3. Bohr effect (Hb can carry more oxygen at a low pCO2 than it can at a high pCO2)
80
Q

loss CO2 makes FETAL blood

A

more alkaline

81
Q

increased CO2 in MATERNAL blood makes it:

A

more acidic

82
Q

diffusion of CO2

A

thru simple diffusion

83
Q

diffusion of food stuff

A

thru facilitated diffusion

84
Q

before 5 weeks, HCG is produced in

A

both syncytio and cytotrophoblasts

85
Q

later, whne maternal serum is at its peak

A

HCG prod in syncytiotrophoblast onlee hehehehehekapoyaperolabanlaaaaaaang

86
Q

HCG detected in plasma of preggy

A

7-9 dayz (after the midcycle surge of LH that precedes ovulation

87
Q

HCG maximal lvls attained at abt 8-10 weeks

A

(peak 100,000 mIU/mL between 60th and 80th days after menses)

88
Q

levels begin to decline by

A

10-12 wks and nadir by 16 wks

89
Q

if corpus luteum is removed before approx 7th week of preg (sometimes 12th wk)

A

spontaneous abortion

90
Q

the corpus luteum involutes slowly after

A

13th-17th week

91
Q

has GH-like bioactivity; demonstrable in placenta within 5-10 days after conception in maternal serum as early as 3 wks after fertilization

A

HPLactogen or HCS

92
Q

It is demonstrated in cytotrophoblasts and later concnted in syncytiotrophoblast

A

Before 6 weeks

93
Q

Rate of secretion is proportional to placental mass

A

Therefore lvls rise steadily until 34-36 weeks

94
Q

HPL actions

A
  1. Lipolysis
  2. Anti insulin
  3. Potent angiogenic hormone
95
Q

Demonstrated in CL, decidua and placenta

A

Relaxin

96
Q

Rise jn maternal circulating relaxin

A

Early pregnancy

97
Q

May act on myometrium to promote relaxation and quiescence of early pregnancy

A

Relaxin

98
Q

Enhancement of GFR

A

Relaxin

99
Q

Large amnts secreted by syncytiotrophoblast during pregnancy

A

Estrogen

100
Q

Serve as estrogen precursors

A

C19 steroids (DHEA-S dehydroepiadrosterone and its sulfate)

101
Q

Quantitatively the most important source of placental estrogen precursors in preg

A

Fetal adrenal gland

102
Q

Effects of estrogen

A

1 enlarge maternal uterus, breast and ductal structures, external genitalia
2 relax the pelvic ligaments (prep for delivery)
3 may affect fetal dev (rate of cell reprod in early embryo)

103
Q

Principal precursor of progesterone biosynthesis

A

Maternal plasma CHOL

104
Q

Progesterone effects

A

1 causes decidual cells to develop (embryo nutrition)
2 decrease uterus contractility
3 dev and conceptus even b4 implantation by increasing secretions of fallopian tubes and uterus to provide appropriate nutritive matter for developing morula and blastocyst
4 helps estrogen prepare mom’$ breasts for lactation

105
Q

By _______, amniotic fluid consists largely of extracellular fluid that diffuses thru fetal skin and thus reflects compo of fetal plasma

A

2nd trimester

106
Q

After _____, composed largely of fetal urine ew ans smol proportion of pulmonary fluid

A

20wwwks

107
Q

Volume increases from 10mL/week at 8 weeks to

A

60mL/week at 21 weeks ans peaks at 34 weeks

REPRODUCTIVE SYSTEM (8 decks)

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