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Embryology > Fetal Membranes and Placenta > Flashcards

Fetal Membranes and Placenta Flashcards

1
Q

What is the Placenta made of

A

Maternal and fetal components, Chorion frondosum and Decidua Basalis

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2
Q

What is the purpose of the placenta ( Hint : 5 )

A

1- protection : prevents microorganisms from reaching fetus ( most of them )
2- Nutrition : provides nutrients from maternal circulation & stores nutrients
3- Respiration : exchanges O2 and CO2 with maternal circulation
4- Excretion : removes waste products from fetal to maternal blood , to be excreted by maternal kidneys
5- Endocrine : placenta takes over progesterone and estrogen release from corpus luteum

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3
Q

Explain the size of the placenta

A

20 cm in length and 2/3 cm in thickness ( 450-600 g )

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4
Q

Why is there a fluctuation of hormones after birth

A

Once the placenta is removed the body has to compensate

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5
Q

What is the Decidua

A

Maternal endometrium in pregnancy

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6
Q

Explain the decidua reaction

A
  • CT reaction of maternal endometrium after implantation happens, prepares the maternal component of the placenta ( AKA: DECIDUA )
  • Progesterone induces increased vascular swelling of stroll cells and accumulation of glycogen granules to provide nourishment source for early embryo
  • Sprouting and ingrowth of capillaries
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7
Q

Explain what happens in Day 7 Fertilization

A

Implantation begins via integral connections and HB-EGF

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8
Q

Explain what happens in Day 8 Fertilization

A

Amniotic sac starts to form

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9
Q

Explain what happens in Day 9 Fertilization

A

Yolk sac starts to form and extra embryonic mesoderm begins to develop

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10
Q

Explain what happens in Day 12 Fertilization

A
  • Extra-embryonic mesoderm surrounds amnion and yolk sac with a specialized mesoderm surrounding
    1- Yolk sac : extra-embryonic splanchnic mesoderm
    2- Amnion : Extra-embryonic somatic mesoderm
  • Trophoblastic lacunae form in syncitotropoblast : primitive fetus vessels
  • Maternal sinusoids encapsulated in syncitotropoblast for nutrients
  • Extraembryonic coelom will start to appear and engulf fetal tissues fetal tissues making chorionic cavity
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11
Q

What is Heuser’s membrane

A

Ring of cells taking origin from hypoblast cells that encapsulates the yolk sac. Secrete connective tissue

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12
Q

Embryo until when , fetus from what

A

Embryo until day 8 , Fetus starting Day 9

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13
Q

What is the chorionic Cavity

A

Sac formed by week 3 from he extra embryonic coelom. The fetal contribution to the placenta . Cavity surrounds fetal tissue but remains connected via extra embryonic mesoderm connecting stalk ( umbilical cord )

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14
Q

Explain the transition from chorion to placenta ( Hint : 3 steps )

A

1- Primary vili : cytotophoblasts
2- Secondary vili: infiltrating extra embryonic mesoderm fills internal cavity
3- Tertiary villi : mesoderm differentiates into small blood vessels and fetal blood

The fetal trophoblast lacunae expands and becomes continuous with maternal blood vessels and endocrine glands : establishing veto-maternal exchange

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15
Q

What happens by Week 5

A

1- Tertiary vili formed
2- cytotrophoblasts encompassed synctiotrophoblasts creating cytotrophoblast shell
3- connecting stalk mesoderm starts to develop fetal capillaries and creating umbilical cord

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16
Q

What happens by end of week 3

A

1- intimating of fetal and maternal vessels connecting
2- Chorion cavity surrounds fetal tissue
3- cytrotrophoblasts proliferate around syncitiotrophoblasts

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17
Q

Explain Get-Maternal Exchange

A

1- Cytotrophoblasts invade endometrial spiral arteries creating hybrid blood vessels
2- maternal blood pools in intervillious space coated by syncytiotrophoblasts
3- nutrients diffuse or actively transferred into chorionic villi that contains fetal capillaries
4- Goes into vessels of connecting stalk and to fetus

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18
Q

What’s the difference between stem and branch vili

A

Stem : reaches from mesoderm to cytotrophoblast shell

Branch :

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19
Q

What happens to the villi barrier as fetus grows

A

It thins as the fetus becomes more developed

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20
Q

Explain features of Decidua

A

1- Decidua Capsularis : covers site where embryo is implanted
2- Decidua Basalis : site of uterus where spiral arteries feed into intervilliious spaces , becomes the placenta
3- Decidua Parietalis : endometrial surface not associated with embryo

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21
Q

What happens by the end of the first trimester

A

Decidua capsiluaris and parietalis fuses with the amniochorionic membrane

22
Q

What is the amniotic sac

A

Membrane fuse to develop amniochorionic membrane that surrounds the amniotic sac which contains the fetus , umbilical cord and up to 1L of amniotic fluid.

23
Q

What is amniotic fluid made of

A

Mainly water and fetal cellular debris. comes from transfer amnioblasts and maternal cells . Exchanged every 3 hours

24
Q

What is the purpose of the amniotic fluid

A

1- Hydrates skin, lungs and GI tract

2- later in gestation urinary tract once activated excretes into amniotic fluid

25
Q

When is the placenta formed

A

Second and third trimester

26
Q

What is Haemolytic Disease in Newborn

A

Haemolytic disease is a RH+ fetus in RH- mom. A problem in second pregnancy after antibodies are produced from first exposure to RH- fetus blood during birth of first pregnancy.
RBC of fetus could be destroyed by maternal immune system .

27
Q

What is the umbilical cord

A

Cord with two umbilical arteries that return deoxygenated blood and waste from fetus to placenta and vein that caries oxygenated blood form placenta to fetus.

28
Q

Umbilical cord abnormalities ( Hint : 4

)

A

1- Single umbilical artery : usually common with genetic conditions
2- Entanglement
3- Compression : prevents flow
4- Prolapse : compression in birth canal

29
Q

What is placenta previa

A

Placenta forms over internal cervix, overlying the birth root. C-sections is required as can cause haemorrhage in mother if vaginal birth. Causes bleeding in pregnancy.

30
Q

What is pre-eclampsia

A

Hypertension and protein in urine after 20 weeks. Abnormal placentation and immunological factors involved.

31
Q

What are the complications of pre-eclampsia

A

Fetus : ischaemia , IUGR

Mother : renal failure, pulmonary oedema , eclampsia

32
Q

What is Wharton’s jelly

A

Springy and strong jelly that encapsulates blood vessels in umbilical cord

33
Q

What is the function of human chorionic gonadotrophin

A

1- Maintains Corpus luteum
2- supports estrogen and progesterone secretion
3- stimulates testosterone secretion form fetus leading cells
4- Basis Pregnancy test

34
Q

What is the function of progesterone in pregnancy

A 
1- maintains uterine lining 
2- inhibits uterine contractions 
3- stimulates mammary glands 
4- forms mucus plug 
5- promotes decidual reaction
35
Q

What is the function of estrogen in pregnancy

A

1- stimulates myometrium growth
2- maintains uterine lining
3- stimulates mammary glands
4- relaxes pelvic joints and ligaments

36
Q

What is the function of the placental parathyroid hormone

A

Increases maternal blood calcium levels for use in calcifying fetal bones

37
Q

What is relaxin

A

Hormone that relaxes pelvic joints and ligaments to help in delivery process

38
Q

What is corticotrophin releasing hormone

A

Hormone that during pregnancy increases HR & BP and stimulates parturition

39
Q

What is Chorionic Somatomammotrophin

A

Hormone that stimulates corpus luteum to secrete hormones and diverts maternal glucose to fetus

40
Q

What inhibits insulin effect during pregnancy

A

Chorionic Somatomammotrophin

41
Q

List types of placental abnormalities

A 
1- Abnormal shape 
2- placenta previa
3- pre-eclampsia 
4- abnormal implantation 
4- trophoblastic disease ( tumours )
42
Q

What are the types of abnormal umbilical insertions

A

1- Marginal ( Batteldore ) : attaches to side instead of middle
2- Velamentous insertion : inserts along edge so fetal blood vessels travel unprotected from placenta

43
Q

List possible placenta implantation abnormalities

A

1- Accerta : invades too deep into the endometrium
2- Incerta : invades myometrium layer
3- Percretia : grows through permetrium

44
Q

What is MAP and what are it’s consequences

A

Morbidly adherent placenta in which tissue is left behind at parturition and can result in haemorrhage or uterus damage.

45
Q

What is Gestational Trophoblastic Disease

A

Molar pregnancies that have tumours

46
Q

What is a complete GTD

A

A non-cancerous condition where the egg has no maternal DNA, no baby being developed

47
Q

What is partial GTD

A

Non-cancerous condition where the tumour is only in a part of the fetus and coexists with fetus

48
Q

What is Invasive GTD

A

A cancerous tumour that arises from benign moles progressing

49
Q

What is Choriocarcinoma

A

Cancerous tumour that arises many years after last pregnancy and metastasizes to other tissues ( lungs )

50
Q

What is placental site GTD

A

Tumour that arises closer to time of pregnancy from intermediate trophoblast cells

Embryology (4 decks)

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