Implantation, Placentation And Hormone Changes In Pregnancy

Question 1

What is a blastocyst?

Answer 1

Embryo that is ready for implantation

Question 2

How old is a blastocyst?

Answer 2

5/6 days post fertilisation

Question 3

What are the two definitive cell lines in a blastocyst?

Answer 3

Embryoblast and trophoblast

Question 4

What does the trophoblast give rise to?

Answer 4

Placenta

Question 5

What does the embryoblast give rise to?

Answer 5

Foetus

Question 6

What is another name for the embryoblast?

Answer 6

Inner cell mass

Question 7

What is the fluid filled cavity of the blastocyst called?

Answer 7

Blastocoel

Question 8

What is the embryoblast end called?

Answer 8

Embryonic pole

Question 9

What is the end that doesn’t have the embryoblast called?

Answer 9

Abembryonic pole

Question 10

What do you need for implantation to occur?

Answer 10

A fully developed blastocyst and a receptive endometrium

Question 11

What is special about the endometrium that allows implantation to happen?

Answer 11

Thick endometrial lining and expression of embryo receptivity markers

Question 12

What are the factors that mean the blastocyst is ready to be implanted?

Answer 12

Fully expanded and hatched out of the zona pellucida

Question 13

What do you get before the blastocyst stays fully expanded?

Answer 13

Expansions and contractions that allow it to exit the zona pellucida

Question 14

What happens at the abembryonic end when the blastocyst is still in the zona pellucida?

Answer 14

Digestive enzymes are released to break down the zona pellucida

Question 15

What are the stages of implantation?

Answer 15

Apposition, attachment and invasion

Question 16

What is apposition?

Answer 16

Positioning of the embryo so its ready to attach to the endometrium

Question 17

What is the surface of the endometrial wall called?

Answer 17

Decidua basalis

Question 18

What happens at days 7-8?

Answer 18

Blastocyst attaches to the decidua basalis and the trophoblast cells assemble to form a synctiotrophoblast

Question 19

Why do the trophoblast cells form a synctotrophoblast?

Answer 19

To facilitate invasion of the decidua basalis

Question 20

What happens at days 9-11?

Answer 20

The synctiotrophoblast further invades the decidua basalis and by day 11 its almost completely buried in the decidua

Question 21

What happens at day 12?

Answer 21

Decidualisation happens and is taken up by the synctiotrophoblast

Question 22

What is decidualisation?

Answer 22

Progesterone causing the enlargement and coating of the decidual cells in glycogen and lipid rich fluid

Question 23

Why is the decidual fluid taken up by the synctiotrophoblast?

Answer 23

Helps to sustain the blastocyst before placental formation

Question 24

What happens around day 14?

Answer 24

Synctiotrophoblast cells branch out to form primary villi.
Decidual cells between the primary villi clear out leaving spaces
Maternal vessels grow into the decidua basalis
Blood filled lacunae merge into a single large pool of blood

Question 25

What is the junctional zone?

Answer 25

The large pool of blood formed when the blood filled lacunae merge

Question 26

What is the junctional zone the foundation for?

Answer 26

The placenta formation

Question 27

What are lacunae?

Answer 27

Spaces left by the evacuation of decidual cells

Question 28

What does the foetal placenta take up?

Answer 28

Oxygen and glucose, immunoglobulins, hormones and some toxins

Question 29

What does the foetal placenta drop off?

Answer 29

CO2 and waste products

Question 30

What happens at day 17?

Answer 30

Foetal mesoderm cells start to form blood vessels in the villi, which grow larger in size

Question 31

What is formed from the villi cells at day 17?

Answer 31

Chorionic plate

Question 32

When do capillaries connect with the umbilical cord blood vessels?

Answer 32

Week 5

Question 33

What is a cotyledon?

Answer 33

Sections of the placenta formed by the decidual septum

Question 34

What are the functions of the placenta?

Answer 34

Maternal provision of nutrients, metabolism, barrier to pathogens and drugs, removal of foetal waste products and endocrine secretion

Question 35

What hormones does the placenta secrete?

Answer 35

Oestrogen, progesterone, hPL, hCG and cortisol

Question 36

Why is the placenta good at its job?

Answer 36

Huge maternal uterine blood supply at a low pressure, high SA in contact with maternal blood

Question 37

What are the risk factors for pre-eclampsia?

Answer 37

First pregnancy, multiple gestation, >35 yrs maternal age, hypertension, diabetes, obesity and family history

Question 38

What is eclampsia?

Answer 38

Pre-eclampsia and seizures

Question 39

What is pre-eclampsia characterised by?

Answer 39

Narrowing of the maternal spiral arteries supplying blood to the placenta

Question 40

What does pre-eclampsia cause?

Answer 40

New onset maternal hypertension and proteinuria

Question 41

What does pre-eclampsia result in?

Answer 41

Placental insufficiency

Question 42

What is placental insufficiency?

Answer 42

Not enough maternal blood flow to the placenta

Question 43

Why do seizures happen in eclampsia?

Answer 43

Higher pressure of blood flow to brain

Question 44

What is a placental abruption?

Answer 44

Premature separation of all or part of the placenta

Question 45

What are the risk factors for placental abruption?

Answer 45

Blunt force trauma, smoking and recreational drug use, multiple gestation, high maternal age and a previous placental abruption

Question 46

What is placental abruption caused by?

Answer 46

The degeneration of maternal arteries supplying blood to the placenta, causing vascular rupture and haemorrhage

Question 47

What are the symptoms of a placental abruption?

Answer 47

Vaginal bleeding and pain in the back and abdomen

Question 48

What are the maternal complications of placental abruption?

Answer 48

Hypovolemic shock, Sheehan syndrome, renal failure and disseminated intramuscular coagulation

Question 49

What is disseminated intravascular coagulation and what causes it?

Answer 49

Blood clots throughout circulation, caused by the release of thromboplastin

Question 50

What is Sheehan syndrome?

Answer 50

Perinatal pituitary necrosis

Question 51

What does Sheehan syndrome cause?

Answer 51

Loss of secondary sexual characteristics (body hair, breast shrinkage and irregular menstural cycles)

Question 52

What are the foetal complications of placental abruption?

Answer 52

Intrauterine hypoxia and asphyxia and premature birth

Question 53

What is placenta previa?

Answer 53

When the placenta implants into the lower uterus, fully or partially covering the internal cervical os

Question 54

What is placenta previa associated with?

Answer 54

Increased chances of pre-term birth and foetal hypoxia

Question 55

What are the risk factors for placenta previa?

Answer 55

Previous c-section, uterine/endometrial surgery or uterine fibroids, previous placenta previa, smoking and recreational drug use, multiple drug use, multiple gestation and a high maternal age

Question 56

What happens hormonally once implantation of the blastocyst has occurred?

Answer 56

hCG production

Question 57

What does oestrogen cause in pregnancy?

Answer 57

Increased blood volume, shallow breathing, increased urinary output

Question 58

What does progesterone cause in pregnancy?

Answer 58

Mood changes, nausea and taste changes, loosened ligaments, breast changes and darkened skin