Fertilization And Placental Development

Question 1

The morula becomes a ?

Answer 1

Blastocyst

Question 2

The blastocyst thins out and becomes?

Answer 2

Trophoblast, which starts placenta

Question 3

The inner cell mass creates?

Answer 3

An embryonic pole

Question 4

Inner cell mass differentiates into?

Answer 4

Epiblast and hypoblast

Question 5

Epiblast forms?

Answer 5

Embryo

Question 6

Hypoblast forms?

Answer 6

Extraembryonic membranes and primary yolk sac

Question 7

Amniotic cavity develops within?

Answer 7

The epiblast mass

Question 8

When does gastrulation happen?

Answer 8

Days 16+

Question 9

What gives rise to all three germ layers?

Answer 9

Epiblast

Question 10

What does syncytiotrophoblast do?

Answer 10

Invade the decidua (endometrium)

Question 11

What do cytotrophoblasts do?

Answer 11

Erode maternal spiral arteries and veins

Question 12

Difference between cytotrophoblast cells and synctiotrophoblast cells?

Answer 12

CT- undifferentiated stem cells
ST- fully differentiated cells
ST- produce placental hormones
CT give rise to ST
CT reduce in number as pregnancy advances

Question 13

Protein transfer across placenta is?

Answer 13

Poor, only occurs by pinocytosis

Question 14

When does transfer of maternal antibodies igG happen?

Answer 14

At 12 weeks, but mostly after 34 weeks hence lack of protection for premature infants

Question 15

Names of decidua?

Answer 15

Capsularis- covers embryo and chorionic cavity

Parietalis- side uterus not occupied by embryo

Basalis- between uterine wall and chorionic villae

Question 16

Umbilical cord insertions?

Answer 16

Marginal- 8.5% increased risk of placental insuffiency

Velamentous- 0.5-2.4% unprotected blood vessels running in membranes risk of vasa praevia fetal haemoorhage

Central- normal

Succenturiate lobe- smaller accessory placental lobe separate from placenta- no concern

Question 17

Vasa praevia?

Answer 17

where one or more of the baby’s placental or umbilical blood vessels cross the entrance to the birth canal under the baby

Question 18

Consequences of placenta praevia?

Answer 18

Massive bleeding in pregnancy
Painless bleeding
Fetal death
Maternal death

Question 19

Failure of trophoblastic invasion into maternal circulation at 12 and 18 weeks leads to?

Answer 19

Poor maternal fetal mixing of blood
Lack of oxygen and nutrients to the fetus
Leads to Fetal Growth Restriction
Pre-eclampsia (raised Blood Pressure)

Question 20

Placenta accreta is?

Answer 20

Placenta unable to separate at birth – uterus can not contract down and massive bleeding. Treatment hysterectomy.

Question 21

Placenta percreta?

Answer 21

Attaches so deeply invades through organs

Question 22

If morula cleaves then preganancy will be?

Answer 22

Dichorionic, diamniotic

Question 23

If blastocyst cleaves pregnancy will be?

Answer 23

Monochorionic, diamniotic

Question 24

If an implanted blastocyst cleaves pregnancy will be?

Answer 24

Monochorionic monoamniotic

Question 25

If formed embryonic disk cleaves pregnancy will be?

Answer 25

Conjoined twins