Lecture 6.1: Placental Development and Pregnancy

Question 1

What does the Trophoblast differentiate into? (2)

Answer 1

• Syncytiotrophoblast
• Cytotrophoblast

Question 2

What does the Embryoblast differentiate into? (2)

Answer 2

• Epiblast
• Hypoblast

Question 3

Which trophoblast differentiate invades the uterine wall? On what day?

Answer 3

• Syncytiotrophoblast
• Day 6

Question 4

Degraded contents of uterine cells engulfed by the trophoblast are used to feed the embryo until….?

Answer 4

links with maternal capillaries are made

Question 5

What day does the bilaminar disk form?

Answer 5

Day 7-9

Question 6

By the end of week 2: what are the 2 cavites surrounding the embryo?

Answer 6

• Amniotic Cavity
• Yolk Sac

Question 7

What is the supporting sac at the end of week 2 called?

Answer 7

Chorionic Cavity

Question 8

What is the role of the yolk sac?

Answer 8

Provides nutrients until placenta ready to take over

Question 9

What does the Chorion go on to form? What is its role?

Answer 9

• Placenta
• Provide Nutrition for Embryo

Question 10

What does the Allantois go on to form? What is its role?

Answer 10

• Umbilical Chord
• Waste Disposal

Question 11

What is the Amnion?

Answer 11

Membrane surrounding amniotic fluid

Question 12

Twins: When are there 2 chorions and 2 amnions?

Answer 12

• 2 morulas and 2 blastocytes
• Could be 2 separate eggs or 1 egg splits into 2 at
  zygotic stage
• Separate implantation sites

Question 13

Twins: When are there 2 amnions but a shared chorion?

Answer 13

• 1 morula but 2 ICMs and bilaminar disks

Question 14

Twins: When are there is shared amnions and a shared chorion?

Answer 14

• 1 blastocyte and bilaminar disk but 2 primitive streaks

Question 15

The human placenta is haemomonochorial, what does this mean?

Answer 15

Only one layer of trophoblast ultimately separates maternal blood from foetal capillary wall

Question 16

Why does the placental membrane get thinner?

Answer 16

To fulfil the needs of the foetus as they increase

Question 17

What are the aims of the implantation of a foetus? (3)

Answer 17

• Establish the basic unit of exchange (villi)
• Anchor the placenta
• Establish maternal blood flow within the placenta

Question 18

What are Primary Villi?

Answer 18

Early finger-like projections of trophoblast

Question 19

What are Secondary Villi?

Answer 19

Invasion of mesenchyme into core

Question 20

Tertiary Villi

Answer 20

Invasion of mesenchyme core by foetal vessels

Question 21

What is Decidualisation?

Answer 21

Functional and morphological changes that occur within the endometrium to form the decidual lining into which the blastocyst implants

Question 22

What hormone signals to the endometrium to prepared
for implantation each month?

Answer 22

Progesterone

Question 23

What do endometrial stromal cells do?

Answer 23

Secrete growth factors and signalling molecules

Question 24

What do uterine natural killer cells do?

Answer 24

Regulate the immune response against the non-self embryo

Question 25

What happens in remodelling of the spiral arteries?

Answer 25

Modifies the arteries from low-flow, high-resistance to high-flow, low-resistance vessels

Question 26

Why does remodelling of the spiral arteries occur?

Answer 26

Maintains the high flow required to meet foetal demand

Question 27

What happens to the cytotrophoblast layer of the placenta as pregnancy progresses?

Answer 27

It is lost, as placenta becomes thinner so that nutritional needs of foetus can be better met

Question 28

What structure links placental blood vessels with developing foetus?

Answer 28

Umbilical Chord

Question 29

What vessels does the umbilical chord contain?

Answer 29

* Two umbilical arteries (deoxygenated blood from foetus to placenta) * One umbilical vein (oxygenated blood from placenta to foetus)

Question 30

What are the 3 ways the placenta allows transport of materials from mother to foetus?

Answer 30

* Simple Diffusion * Active Transport * Facilitated Diffusion

Question 31

What materials are transported via Simple Diffusion between mother and foetus? (4)

Answer 31

* Water * Electrolytes * Urea & uric acid * Gases (foetal O2 stores are small so maintenance of adequate flow is essential)

Question 32

What materials are transported via Facilitated Diffusion between mother and foetus?

Answer 32

Glucose

Question 33

What materials are transported via Active Transport between mother and foetus? (3)

Answer 33

* Specific “transporters” expressed by the syncytiotrophoblast * Amino Acids * Iron * Vitamins

Question 34

How is Passive Immunity passed from mother to foetus? What Ig specifically?

Answer 34

* Receptor-mediated transport process * IgG

Question 35

The Placenta is also involved in metabolism, what substances does it synthesis? (3)

Answer 35

* Glycogen * Cholesterol * Fatty acids

Question 36

Why does the placenta synthesise glycogen?

Answer 36

Storage of maternal glucose for transfer to foetus later as necessary

Question 37

Why does the placenta synthesise cholesterol?

Answer 37

It is a precursor for oestrogen and progesterone

Question 38

What steroid hormones does the placenta produce? (2)

Answer 38

* Oestrogen * Progesterone

Question 39

What protein hormones does the placenta produce? (4)

Answer 39

* Human Chorionic Gonadotrophin (hCG) * Human Chorionic Stomatomammotrophin * Human Chorionic Thyrotrophin * Human Chorionic Corticotrophin

Question 40

What is a molar pregnancy (hydatidiform mole)?

Answer 40

* A gestational trophoblastic disease (GTD), which originates from the placenta and can metastasise * It is unique in that the tumour originates from gestational tissue rather than from maternal tissue

Question 41

What is a choriocarcinoma?

Answer 41

A malignant, fast-growing tumour that develops from trophoblastic cells

Question 42

What effect does placental progesterone have on maternal metabolism?

Answer 42

Causes increased appetite

Question 43

What effect does hCS/hPL have on maternal metabolism?

Answer 43

Increases glucose availability to foetus by switching mother from glucose to fatty acid metabolism

Question 44

What effects does Relaxin have on the mother? (4)

Answer 44

* Increases flexibility of pubic symphysis * Increases size of pelvis * Suppresses oxytocin release thereby preventing premature labour * Causes dilation of cervix before delivery

Question 45

Dysfunctions in Implantation: Ectopic Pregnancy

Answer 45

Implantation at site other than uterus (most commonly fallopian tubes)

Question 46

Dysfunctions in Implantation: Complication of Lower Uterine Implantation (3)

Answer 46

* Placenta Praevia (placenta attaches in the lower part of your uterus, sometimes completely covering the cervix) * Haemorrhage in Pregnancy or during Birth * Require C-section

Question 47

Dysfunctions in Placental Invasion

Answer 47

Inadequate invasion of trophoblasts to reach the maternal vessels

Question 48

What teratogens can access the foetus via the placenta? (5)

Answer 48

* Thalidomide * Alcohol * Therapeutic drugs * Drugs of abuse * Maternal smoking

Question 49

What is haemolytic disease of the newborn?

Answer 49

Occurs when the immune system of the mother sees a baby's RBCs as foreign, Rhesus blood group incompatibility of mother and foetus

Question 50

What maternal systems/physiological change during pregnancy? (6)

Answer 50

* Cardiovascular System * Urinary System * Respiratory System * Metabolic Changes * Gastrointestinal System * Immune System

Question 51

What happens to blood volume during pregnancy?

Answer 51

It Increases

Question 52

Is BP affected by pregnancy?

Answer 52

Systolic BP is never normally increased in pregnancy

Question 53

What is Pre-eclampsia?

Answer 53

Having high blood pressure (hypertension) and protein in your urine (proteinuria) during pregnancy

Question 54

How is Pre-eclampsia treated?

Answer 54

Deliver the baby

Question 55

What is Eclampsia?

Answer 55

Eclampsia is unexplained generalised seizures in patients with preeclampsia

Question 56

What changes occur in the urinary system during pregnancy? (7)

Answer 56

* Glomerular filtration rate (GFR) increases * Renal plasma flow increases * Filtration capacity intact * Functional renal reserve decreases as GFR increases * Increased kidney volume * Ureter dilation * Increased bladder capacity

Question 57

What happens to cardiac output, stroke volume, heart rate in pregnancy?

Answer 57

Increases

Question 58

What happens to systematic vascular resistance and blood pressure in pregnancy?

Answer 58

Decreases

Question 59

What happens to the subcostal angle during pregnancy?

Answer 59

Increases

Question 60

What increases in the respiratory system during pregnancy? (3)

Answer 60

* Subcostal Angle * Anterior-Posterior and Transverse Diameters of the Chest Wall * Chest Wall Circumference

Question 61

What provides substrate for maternal metabolism, leaving glucose for the foetus?

Answer 61

Free fatty acids

Question 62

What is Gestational Diabetes?

Answer 62

Occurs when your body can't make enough insulin during your pregnancy, thus increased blood sugar levels

Question 63

Effects of Gestational Diabetes on Baby

Answer 63

* Baby being very large * Being born early * Having low blood sugar after birth

Question 64

Effects of poorly controlled Gestational Diabetes on Baby (3)

Answer 64

* Congenital Defects * Developing type 2 diabetes later in life * Having low blood sugar after birth (baby will have hyperinsulin due to mother's diabetes)

Question 65

Pregnancy is a pro-thrombotic state, what does this increase risk of? (4)

Answer 65

* VTE/DVT * PE * Heart Attack * Stroke

Question 66

Why can Anaemia occur in Pregnancy?

Answer 66

If you don't have enough iron stores or folate, you could develop iron deficiency anaemia

Question 67

Effects of pregnancy related anaemia on foetus (2)

Answer 67

* Increases the risk of premature birth * Baby may not grow as much as it should

Question 68

What are the diagnostic criteria for pre-eclampsia (3)

Answer 68

* Thrombocytopenia * Proteinuria * Hypertension