Placenta

Question 1

Which cell type is the chorion derived from?

Answer 1

Trophoblasts

Question 2

State the two type of chorion

Answer 2

Smooth chorion (chorion leave)
Villus chorion (chorion frondosum) - arrives from the embryonic pole

Question 3

Which 3 maternal and fetal layers fuse at the abevbryonic pole?

Answer 3

1. Amniotic membrane
2. Chorion leave
3. Decidua parietalis

Question 4

What is the abevbryonic pole?

Answer 4

The pole of the blastocyst (opposite the embryonic pole where the embryo blast is located) attached to the mother

Question 5

How does the placenta develop on day 12-14?

Answer 5

The syncytiotrophoblasts within the cytotropphoblasts have implanted into the uterine wall. Lacunae from the syncytiotrophoblasts tart to link with maternal blood vessels

Question 6

How has the placenta developed on day 15

Answer 6

The syncytiotrophoblast layer is outside the cytotrophoblast layer. Lacunae link with maternal blood vessels. Decidua is the outermost layer

Question 7

What occurs on day 16 of placental formation?

Answer 7

Cytotrophoblasts proliferate into the syncytiotrophoblasts to form the primary villus.

Question 8

What occurs on day 17 of placental formation?

Answer 8

Extra-embryonic mesoderm contributes to the chorion and proliferates into cytotrophoblast and syncytiotrophoblast layers to form the secondary villi

Question 9

Why do the smooth chorion villi degenerate at week 5

Answer 9

Poor blood supply

Question 10

Describe the amniochorion at weeks 8-25

Answer 10

The amnion and smooth chorion fuse. The decidua parietals and capsular fuse.
These fusions result in the loss of the uterine lumen

Question 11

How does the placenta develop in weeks 8-25

Answer 11

Proliferation of the villus chorion to provide an excellent blood supply

Question 12

What is an accessory placenta and what is its clinical relevance?

Answer 12

Forms where blood supply remains but can cause postpartum haemorrhage in the mother

Question 13

Blood supply of placenta

Answer 13

Umbilical vein brings oxygenated blood to fetus whereas umbilical arteries bring deoxygenated blood back to mother

Question 14

Which structure connects the term placenta to the maternal blood supply?

Answer 14

Chorionic villus

Question 15

How does substance exchange occur in the term placenta?

Answer 15

Via the spiral arteries

Question 16

Define placental abruption

Answer 16

Premature separation of placenta from uterine wall

Question 17

Define placenta praevia

Answer 17

Implantation occurs in the lower uterine segment and acmes out before the baby (can cause haemorrhage)

Question 18

Define placenta accreta

Answer 18

Implantation is too deep into the myometrium (may cause postpartum haemorrhage if placenta doesn’t separate

Question 19

Define pre-eclampsia

Answer 19

Implantation is too shallow

Question 20

Give 3 effects of pre-eclampsia

Answer 20

1. Hypertension
2. Significant proteinuria
3. Increased placenta resistance

Question 21

When does pre-eclampsia present?

Answer 21

Around 20 weeks