Fetal Membranes and Placenta Flashcards by Joyce Beshara

What is the Placenta made of

Maternal and fetal components, Chorion frondosum and Decidua Basalis

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

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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Explain the size of the placenta

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

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Why is there a fluctuation of hormones after birth

Once the placenta is removed the body has to compensate

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What is the Decidua

Maternal endometrium in pregnancy

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Explain the decidua reaction

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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Explain what happens in Day 7 Fertilization

Implantation begins via integral connections and HB-EGF

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Explain what happens in Day 8 Fertilization

Amniotic sac starts to form

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Explain what happens in Day 9 Fertilization

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

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Explain what happens in Day 12 Fertilization

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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What is Heuser’s membrane

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

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Embryo until when , fetus from what

Embryo until day 8 , Fetus starting Day 9

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What is the chorionic Cavity

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

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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What happens by Week 5

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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What happens by end of week 3

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

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Explain Get-Maternal Exchange

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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What’s the difference between stem and branch vili

Stem : reaches from mesoderm to cytotrophoblast shell

Branch :

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What happens to the villi barrier as fetus grows

It thins as the fetus becomes more developed

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Explain features of Decidua

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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What happens by the end of the first trimester

Decidua capsiluaris and parietalis fuses with the amniochorionic membrane

What is the amniotic sac

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

What is amniotic fluid made of

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

What is the purpose of the amniotic fluid

1- Hydrates skin, lungs and GI tract

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

When is the placenta formed

Second and third trimester

What is Haemolytic Disease in Newborn

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 .

What is the umbilical cord

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.

Umbilical cord abnormalities ( Hint : 4 | )

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

What is placenta previa

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.

What is pre-eclampsia

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

What are the complications of pre-eclampsia

Fetus : ischaemia , IUGR | Mother : renal failure, pulmonary oedema , eclampsia

What is Wharton's jelly

Springy and strong jelly that encapsulates blood vessels in umbilical cord

What is the function of human chorionic gonadotrophin

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

What is the function of progesterone in pregnancy

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

What is the function of estrogen in pregnancy

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

What is the function of the placental parathyroid hormone

Increases maternal blood calcium levels for use in calcifying fetal bones

What is relaxin

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

What is corticotrophin releasing hormone

Hormone that during pregnancy increases HR & BP and stimulates parturition

What is Chorionic Somatomammotrophin

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

What inhibits insulin effect during pregnancy

Chorionic Somatomammotrophin

List types of placental abnormalities

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

What are the types of abnormal umbilical insertions

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

List possible placenta implantation abnormalities

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

What is MAP and what are it's consequences

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

What is Gestational Trophoblastic Disease

Molar pregnancies that have tumours

What is a complete GTD

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

What is partial GTD

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

What is Invasive GTD

A cancerous tumour that arises from benign moles progressing

What is Choriocarcinoma

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

What is placental site GTD

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