Yan: Placenta

Question 1

In the blastocyst, what is the inner cell mass called? The outer cell mass?

Answer 1

embryoblast; trophoblast

Question 2

What happens on day 6?

Answer 2

invasion of the uterine epithelium by trophoblast cells of the blastocyst

Question 3

What happens on day 8?

Answer 3

trophoblast forms 2 layers: cytotrophoblast and syncytiotrophoblast

Question 4

What happens on day 9?

Answer 4

trophoblast enters lacunar stage –> vacuoles form and fuse to form lacunae
formation of primitive yolk sac

Question 5

On what day is uteroplacental circulation established?

Answer 5

Day 11 and 12

Question 6

Formation of uteroplacental circulation: trophoblastic lacunae and (blank) integrate and (blank) enters the lacunar system

Answer 6

maternal sinusoids; maternal blood

Question 7

On day 13, what forms?

Answer 7

primary villi

Question 8

How do primary villi form?

Answer 8

cytotrophoblastic cell proliferation and penetration into syncytiotrophoblast –> cellular columns –> villi formation

Question 9

What two things make up the primary villus?

Answer 9

cytotrophoblastic core + syncytial layer

Question 10

What happens to a primary villus to make it a secondary villus?

Answer 10

mesodermal cells penetrate the core of the primary villi

Question 11

What happens to a secondary villus to make a definitive villus?

Answer 11

blood vessels derive from mesoderm cells in definitive villi

Question 12

At the end of 3rd week, maternal vessels penetrate the (blank) shell to enter (blank) spaces, which surround the villi. Capillaries in the (blank) are in contact with vessels in the chorionic plate and the connecting stalk, which in turn are connected to intraembryonic vessels.

Answer 12

cytotrophoblastic; intervillous; villi

Question 13

Intervillous spaces of the blood contain (blank) blood, while (blank) blood is contained in the villi.

Answer 13

maternal; fetal

Question 14

At the end of 3rd week, 3rd and 2nd villi give the trophoblast a radial shape. Intervillous spaces are lined with (blank). Cytotrophoblastic cells surround the entire trophoblast and in contact with endometrium. The embryo is suspended in the chorionic cavity by the (blank).

Answer 14

syncytium; connecting stalk

Question 15

In the fourth week, there is a 4 layer barrier between maternal and fetal blood. What are the layers?

Answer 15

1. syncytium
2. cytotrophoblast
3. CT
4. endothelium

Question 16

By the fourth month, there are only two layers - what are they? Blood vessels move and make contact with the synctiotrophoblast cells.

Answer 16

1. syncytium

2. endothelium

Question 17

By end of (blank) month, villi have disappeared at the abembryonic pole, forming chorion laeve

Answer 17

2nd

Question 18

By end of the (blank) month, the amnion and chorion have fused and the uterine cavity is obliterated by fusion of the chorion laeve and decidua parietalis.

Answer 18

3rd

Question 19

T/F: Full-term placenta is shed off uterine wall in 30 mins after child birth.

Answer 19

True

Question 20

There is a separation between fetal and maternal circulation during placental development, because the fetal circulation is confined within the (blank) and maternal blood confined to (blank).

Answer 20

villi; intervillus space

Question 21

Function of the placenta

Answer 21

exchange of gases
exchange of nutrients and electrolytes
transmission of maternal antibodies (gain of passive immunity)
hormone production

Question 22

During pregnancy, the (blank) provides the main source of hormones – there is a duel supply initially from the corpus luteum and the placenta. When placental nutrition is efficient, corpus luteum will degenerate.

Answer 22

placenta

Question 23

Hormones produced by the placenta and in what part are they produced?

Answer 23

progesterone
estrogens
hCG
somatomammotropin
produced in the syncytiotrophoblast

Question 24

On what day is the fibrin coagulum formed up to close the penetration defect?

Answer 24

Day 9

Question 25

On what day is the primitive yolk sac formed?

Answer 25

Day 9