Fetal development and Embryology

Question 1

Describe the process of sperm production.

Answer 1

The process starts with the mitotic division (duplication) of the stem cell located inside the basement membrane of the tubules inside the testes. Then, each of the duplicated stem cells (46 chromosomes) will undergo meiosis division to become the sperm cells that have 23 chromosomes.

Question 2

Why do men have unlimited sperm cells?

Answer 2

Their sperm cells duplicate themselves before developing so they never run out of copies. However the fact that they duplicate then divide mean that there is more of a chance of genetic errors.

Question 3

How long does the maturation process of sperm take?

Answer 3

Around 24 days. This means that if the father uses any toxic substances like smoking or drugs then it can effect the sperm for almost a month

Question 4

What is capacitation?

Answer 4

The maturation that the sperm have to go through in order for fertilisation to happen. This happens inside the female genital tract. The female body sends chemical substances that will unlock certain receptors in the sperm. Which make it capable of reacting to the environment of the female body.

Question 5

What is triggered by an orgasm?

Answer 5

Strong uterine contractions then suction up the sperm into the uterine cavity.

Question 6

What are the 3 stages of fetal development?

Answer 6

Pre embryonic: until implantation
Embryonic: 2-8 weeks
Fetal: week 9 to birth

Question 7

What happens to the zygote within 24 hours?

Answer 7

The zygote undergoes mitosis and splits into smaller cells. This is called cleavage. Day 2 embryo

Question 8

By day 4 what is it called?

Answer 8

Morula and has 16-20 cells

Question 9

What is it called at day 10?

Answer 9

The blastocyst

Question 10

What happens of the 5th day?

Answer 10

Fluid accumulates in the space between the peripheral and central cells of the morula and becomes the hollow blastocyst

Question 11

What happens when the fluid penetrates the morula?

Answer 11

It divides the cell into 2 main areas: the inner cells becomes the embryoblast and the flattened outer cells

Question 12

What will the embryoblast become?

Answer 12

The embryo

Question 13

What will the flattened outer cells become?

Answer 13

The placenta

Question 14

What is the layer of flattened outer cells called?

Answer 14

Trophoblast

Question 15

What was the ectoderm form?

Answer 15

Skin, hair and nervous system

Question 16

What does the mesoderm form?

Answer 16

Muscle, bones, connective tissue, blood vessels, blood and urogenital glands

Question 17

What does the endoderm form?

Answer 17

lining of the digestive, respiratory and urinary systems and glandular cells like the liver and pancreas

Question 18

Why are women advised to take a folic acid supplement?

Answer 18

Because the process of the neural tube closure is mediated by folic acid.

Question 19

What happens with the digestive system by week 5?

Answer 19

The liver, gallbladder and pancreas are already developing

Question 20

What happens with the digestive system by week 10?

Answer 20

The liver grows rapidly and occupies most of the abdominal cavity so there is not enough space for the intestines to grow. This is why the intestines start to grow outside the abdominal cavity in the yolk sac and then by week 10 it will rotate and fit inside the abdominal cavity

Question 21

What happens if there is a failure in the intestines rotating inside?

Answer 21

This can cause congenital malformations. If the yolk sac doesn’t retract inside then congenital abnormalities in the abdominal wall can lead to babies being born with part of the bowel outside their body.

Question 22

When will the baby start making breathing movements?

Answer 22

11 weeks

Question 23

When can the baby open its eyes?

Answer 23

25 weeks

Question 24

When do the lungs reach full maturation?

Answer 24

34 weeks

Question 25

What will trigger the changes in the maternal body to maintain pregnancy?

Answer 25

The primitive placenta will start producing hCG. This hormone is detected in pregnancy tests

Question 26

What is implantation bleeding?

Answer 26

This is bleeding that some women may experience at the beginning of pregnancy because the trophoblast breaks through the decidua

Question 27

Where does the exchange of nutrients between maternal and fetal blood?

Answer 27

The chorionic villi