Early Stages

Question 1

When is pregnancy calculated?

Answer 1

From the last menstrual period (LMP)

Question 2

When is development calculated from?

Answer 2

Fertilisation

Question 3

What is an oocyte?

Answer 3

The egg cell

Question 4

Where is the egg released from?

Answer 4

Ovary

Question 5

How is the oocyte swept into the oviduct?

Answer 5

The frimbriae

Question 6

Meiosis is only completed when?

Answer 6

When the sperm enters

Question 7

What is cleavage ?

Answer 7

Rapid mitotic cell division

Question 8

Where does the pre-embryo implant?

Answer 8

Into the uterine wall?

Question 9

What is a zygote?

Answer 9

A fertilised egg

Question 10

What does the zygote divide to form?

Answer 10

Blastocyst

Question 11

What can be seen in maternal blood when blastocyst is formed? (2-3 days)

Answer 11

EPF (early pregnancy factor)

Question 12

What is a blastocel?

Answer 12

A hollow ball of cells formed from a zygote

Question 13

What will the inner cell mass of the blastocel form?

Answer 13

The embryo

Question 14

What will the outer cells of the blastocel form?

Answer 14

The trophoblast will form the placenta

Question 15

What forms the chorion?

Answer 15

The trophoblast

Question 16

What is the chorion?

Answer 16

Part of the placenta which enables the fetus to get O2 and nourishment from the mother

Question 17

What is the zona pellucida?

Answer 17

A membrane which surrounds the blastocyst to protect it

Question 18

Before implantation, what does the blastocyst need to do?

Answer 18

Hatch from the zona pellucida

Question 19

What happens at day 6?

Answer 19

The blastocyst attaches to uterine wall

Question 20

What is the risk of the blastocyst being able to implant anywhere?

Answer 20

Ectopic pregnancy

Question 21

What happens if the blastocyst does not implant?

Answer 21

It will leave in menstruation

Question 22

Day 14 may show spotting in the mother and may be mistaken for a period. What does this signify?

Answer 22

The blastocyst being fully embedded

Question 23

What would happen if the blastocyst implants close to the cervix?

Answer 23

The placenta would not be able to be shed so a c-section would be planned

Question 24

What happens to the uterine cavity as the blastocyst grows?

Answer 24

It is pushed together until gap is almost gone

Question 25

What does the trophoblast form when it divides?

Answer 25

The cytotrophoblast and the syncytiotrophoblast

Question 26

What is the characteristic of the cytotrophoblast?

Answer 26

It forms tightly packed cells around the blastocyst

Question 27

What are the characteristics of the syncytiotrophoblast?

Answer 27

Loosely packed cells surrounding the cytotrophoblast

Question 28

What are Lacunae and where do they form?

Answer 28

They are ‘holes’ formed between the loosely packed cells of the syncytiotrophoblast

Question 29

How does the lacunae fill with blood?

Answer 29

The trophoblast cells invade spiral arteries causing a leakage of blood into the lacunae, giving the fetus a blood supply

Question 30

What is the epiblast?

Answer 30

The cell mass in the blastocyst which will form the embryo

Question 31

Some of the cells in the epiblast go on to form what?

Answer 31

The amniotic cavity

Question 32

What does the cytotrophoblast form as it grows?

Answer 32

Villi- primary (frondosum)

Question 33

There is always a membrane separating the embryo from the maternal tissue, what forms this?

Answer 33

The syncytiotrophoblasts that form the Chorion

Question 34

How is the maternal blood supply invaded?

Answer 34

The primary villi grow to form secondary and tertiary villi, forming villi trees which invade the lacunae and also maternal blood supply

Question 35

What is the amniochoronic membrane and what does it do?

Answer 35

Syncytiotrophoblast invades uterine tissue forming the chorion which fuses with the amnio layer. This allows the fetus to get O2 and nourishment

Question 36

What a the placenta?

Answer 36

An organ which provides the fetus with nourishment via the umbilical cord.