Implantation and placental function

Question 1

Where does fertilisation occur

Answer 1

occurs in oviducts

Question 2

Where does fertilised egg move to

Answer 2

Lumen of uterus

Question 3

What is placentation recognition of pregnancy

Answer 3

Establishing physical and nutritional contract

Required for supply of nutrients leading to growth

Question 4

What is maternal recognition of pregnany

Answer 4

Signals presnece to mother and prevents luteal regession

Question 5

What is the first differentiation step

Answer 5

6 days after fertilisation, cells of blastocyst differntaited into trophectoderm
Trophhectoderm will become placenta
Inner mass becomes feotus

Question 6

Define apposition

Answer 6

Positioning of blastocyst within uterine cavity

Question 7

Define adhesion

Answer 7

Cells of trophoblast fix to maternal tissue and each other

Achieved via group of cell adhesion molecules (laminin, fibronectin)

Question 8

What happens during differentiation

Answer 8

Trophectoderm differentiates into cytotrophoblast and syncytiotrophoblast

Question 9

What is cytotrophoblast

Answer 9

Single nucleus which rapidly divides in vivo

Question 10

What syncytiotrophoblasts

Answer 10

Derived from fused cytotrophoblast. Multinucleated

Question 11

Describe placental formation

Answer 11

trophoblasts form villous structures
cytotrophoblasts break through trophoblast shell
invade through decidual tissue
triophoblast reach maternal spinal arteries
spiral arteries widened allowing greater flow of maternal drug

Question 12

What is the barrier between maternal and foetal circulation

Answer 12

Villous trophoblast

Question 13

What regulates invasion

Answer 13

Embryo exists in hypoxic environement

Oxygen gradient between mam and feotus regulates invasion

Question 14

What happens to oocyte during fertilisation

Answer 14

Corpus luteum doesn’t degenerate
Progesterone doesn’t degenerate
Endometrium is maintained

Question 15

When can hCG be detected

Answer 15

4 weeks

Question 16

When does hCG surge

Answer 16

week 10

Question 17

What happens as hCG falls and progesterone and oestrogen increases

Answer 17

Latter two hormones are unstable

Question 18

What does the foetal surface of the placenta

Answer 18

Smooth covered in amnion

Question 19

What does maternal surface of the placenta

Answer 19

Dull, grey divided into contledons

Question 20

What does smaller branches of imbilical artery supply?

Answer 20

Chorionic villi

Question 21

What is main site of exchange in placenta

Answer 21

Capillary networks

Question 22

What is transported in

a) umbilical vein
b) umbilical artery

Answer 22

a) away from maternal side to baby. Oxygenated blood and nutrients
b) away from baby carries waste and deoxygenated blood

Question 23

How many spiral arteries are there in maternal circulation

Answer 23

80-100

Question 24

Functions of placenta

Answer 24

nutrients
prevents luteal regression
site of exchange of gases
nutrient exchange and waste exchange

Question 25

How are water and electrolytes transported across placenta

Answer 25

Simple diffusion

Question 26

How is glucose transported

Answer 26

Facilitated via GLUTS

Question 27

How are amino acids transported across placenta

Answer 27

Active transport via transporter protein

Question 28

Large proteins and cells transported across placenta?

Answer 28

Pinocytosis

Question 29

What does placenta allow through

Answer 29

igG antibodies
hormones
antibiotics
sedatives
some viruses

Question 30

Can foetus cells cross placenta

Answer 30

Y

Question 31

What hormones does placenta secrete?

Answer 31

hCG, hPL, oestrogen, progesterone, human placental growth hormone, insulin growth factors, relaxin

Question 32

What 3 factors help prevent rejection of feotus by maternal immune system?

Answer 32

• Trophoblast cells express HLA G which is not recognised by host immune cells
• Ilfiltrating leucocytes release IL-2 which regulates immune system
• Decidual reaction cells become swollen and tightly packed forming physical barrier