Lecture 13: Extraembryonic Tissues & Placenta

Question 0

What are the amnion and yolk sac derivatives of?

Answer 0

Amnion: epiblast

Yolk sac: hypoblast

Question 1

Name the extraembryonic tissues.

Answer 1

Amnion, Yolk sac, Chorion, & Allantoes

Question 2

What do the chorion and allantois interface with?

Answer 2

Chorion: part of fetal maternal interface
Allantois: placenta via umbilical cord

Question 3

What two things make up the fetal-maternal interface?

Answer 3

Placenta and Chorion

Question 4

What are functions of the amnion?

Answer 4

Buffer against mechanical injury, Accommodate growth, Allow normal movements, & protect fetus from adhesions

Question 5

High levels of alpha-fetoprotein are strong indicators of _____.

Answer 5

Neural tube defects

Question 6

Creatinine or Lecithin-to-sphingomyelin ration can be used to determine what?

Answer 6

Fetal maturity based on maturity of lungs

Question 7

What is hydramnios frequently associated with?

Answer 7

Esophageal atresia or anencephaly

Question 8

What is oligohydramnios frequently associated with?

Answer 8

Renal agenesis

Question 9

What occurs during phase I of amniotic fluid formation?

Answer 9

Diffusion of electrolytes through fetal ectoderm, maternal serum added, secretion by amniotic membrane

Question 10

What occurs during phase II of amniotic fluid formation?

Answer 10

Fetal urine added & filtration for vessels associated with chorion leave

Question 11

What is the turnover rate of amniotic fluid in the 3rd trimester and at term?

Answer 11

3rd trimester: every 3 hours

Term: 500 mL/hour

Question 12

Folic acid and vitamins A, B12, and E may concentrate where?

Answer 12

Yolk sac

Question 13

Where is the site of origin of primordial germ cells and the location of blood islands?

Answer 13

Yolk sac

Question 14

What is histiotrophic nutrition?

Answer 14

Endocytosis of folic acid and vitamins A, B12, & E in the yolk sac

Question 15

What is Meckel’s Diverticulum?

Answer 15

a remnant of the yolk duct that appears as a fibrous cord or out-pouch of the small intestine

Question 16

Where do allantoic vessels form?

Answer 16

Mesoderm of allantois

Question 17

The proximal part of the allantois is also known as _____ and associated with formation of the _____. It then becomes the _____.

Answer 17

Urachus.
Urinary bladder.
Median umbilical ligament

Question 18

In the previllous embryo _____ villi have formed on the trophoblast.

Answer 18

No

Question 19

In the primary villi stage _____, _____, _____primary villi appear.

Answer 19

Solid, cytotrophoblastic, ectodermal

Question 20

In the secondary villous stage, _____ appear within the primary villi.

Answer 20

Mesodermal cores

Question 21

In the tertiary villous stage _____ appear in the mesenchymal core of the secondary villi.

Answer 21

Blood vessels

Question 22

What are hofbauer cells?

Answer 22

Fetal macrophages

Question 23

What do cytotrophoblastic columns do?

Answer 23

Hold placenta in place

Question 24

What is the chorionic plate VS the cytotrophoblastic shell?

Answer 24

Chorionic plate: fetal side. | Cytotrophoblastic shell: covers maternal decidual shells on maternal side

Question 25

Which genes are expressed while the placental villi are being established?

Answer 25

Msx2 & Dlx4

Question 26

The exit from the cell cycle at points of branching on villi is due to what?

Answer 26

Transcription factor Gem-1

Question 27

What are the layers from amnion to outer cytotrophoblastic shell?

Answer 27

Amion-->Chorionic cavity-->Chorionic plate-->Villi-->Syncytiotrophoblast-->Outer cytotrophoblastic shell

Question 28

What is the chorionic leavae?

Answer 28

Area where villi go away because they're not being used

Question 29

What is the pathway of maternal blood flow?

Answer 29

Enters trophoblastic lacunae-->exchange of materials with fetal blood in capillaries-->Exits maternal veins in decidua basalis

Question 30

What is the pathway of fetal blood flow?

Answer 30

Enters capillary beds in villi via umbilical arteries-->Exchange of materials with maternal blood-->Exits capillary bed via umbilical vein