Embryology part 1

Question 1

What are male gametes called?

Answer 1

Sperm

Question 2

Where are male gametes produced ?

Answer 2

testis

Question 3

What cell does sperm develop from ?

Answer 3

A spermatogonium

Question 4

What are female gametes called?

Answer 4

Eggs or ovum

Question 5

Where are female gametes produced?

Answer 5

In the ovaries

Question 6

What cell does eggs develop from ?

Answer 6

Oogonium

Question 7

What is the process of producing gametes called?

Answer 7

Meiosis

Question 8

What does one cycle of meiosis in males give rise to ?

Answer 8

4 sperm

Question 9

What does one cycle of meiosis in females give rise to ?

Answer 9

1 egg and 3 polar bodies which are then destroyed

Question 10

What is fertilisation ?

Answer 10

When the pronucleus of the egg and sperm combine

Question 11

What is the diploid cell produced in fertilisation called?

Answer 11

a zygote

Question 12

Where is mitochondria genetic information from ?

Answer 12

The mother

Question 13

What happen to the zygote after fertilisation ?

Answer 13

It undergoes mitosis and forms a solid ball of cells.

Question 14

What is this solid ball of cells called?

Answer 14

A morula

Question 15

What happens to a morula ?

Answer 15

It then divides and forms a blastocyst

Question 16

Why does a blastocyst form ?

Answer 16

Diffusion is not sufficient to get things from the outside

Question 17

What then happens to the blastocyst ?

Answer 17

It splits into two. This forms the trophoblast (outer layer) and the inner mass of cells.
A cavity forms in the centre and nutrient can get to the tissue faster.

Question 18

Why does the placenta need to from ?

Answer 18

it is a better method of getting nutrients into all the cells

Question 19

When does the baby become dependant on the placenta?

Answer 19

At week 12

Question 20

Where does fertilisation take place ?

Answer 20

In the fallopian tube

Question 21

Where is the morula ?

Answer 21

Moving down the fallopian tube

Question 22

Where is the blastocyte ?

Answer 22

In the uterus

Question 23

How does the zygote and morula move down the fallopian tube ?

Answer 23

Cillia.

Question 24

What happens if the cillia in the fallopian tube is not working ?

Answer 24

Ectopic pregnancy

Question 25

How many days dose it take to travel down the fallopian tube ?

Answer 25

6-7 days

Question 26

When is ovulation in relation to a period ?

Answer 26

14 days before the period starts

Question 27

What is implantation ?

Answer 27

The process where the blastocyte buries itself into the endometrial lining.

Question 28

What part of the blastocyte controlled implantation ?

Answer 28

The trophoblast

Question 29

What does the trophoblast divide to from ?

Answer 29

Two layers creating the chorion

Question 30

Why is the chorion important in implantation ?

Answer 30

It develops chorionic villi which burry into the endometrium lining,

Question 31

How do pregnancy tests work ?

Answer 31

They detect HCG which is released by the chorion

Question 32

What is HCG ?

Answer 32

A hormone used to prevent the sheading of the endometrial lining.

Question 33

What is the endothelial lining called once’s it has been implanted in ?

Answer 33

The decidua basalis

Question 34

Describe what happens to the inner cell mass ?

Answer 34

Flattens and forms two layered disc.

Question 35

What are the two layers of the inner cell mass disc called?

Answer 35

The epiblast and the hypoblast

Question 36

What are the two cavities created by the inner cell mass disc called?

Answer 36

Amniotic cavity and the yolk sac

Question 37

What are fraternal twins ?

Answer 37

Non-identical twins created when two ova are released and both fertilised.

Question 38

What structures does the trophoblast continue to develop and create ?

Answer 38

The umbilical cord, foetal blood vessels, placenta

Question 39

What happens to the bilaminar disc?

Answer 39

• Primitive streak forms creates an axis
• Gastrulation
  (Epiblast cells migrate to lie between the epiblast and the hypoblast layers
• These cell displace the hypoblast and form a trilaminar
• The ectoderm, the mesoderm and the endoderm)

Question 40

What happens after gastrulation ?

Answer 40

The ectoderm starts to descend down and forms a ball of cells which become disconnected from the ectoderm this is called the notochord.

Question 41

What is neurulation ?

Answer 41

Now the ectodermal cells in the primitive streak will thicken and form a neural plate which will drip down forming a valley will two hills on either side. The two hills join and the neural tube is disconnected from the ectoderm. This will happen along the whole length if the primitive streak. The top develops to form the brain and the rest the spinal cord. The formation of the neural tube is called neurulation. To some extent this can been seen in our spinal cord.

Question 42

What happens to the mesoderm after neurulation ?

Answer 42

Mesoderm thickens and then separates into three parts.

The paraxial mesoderm, the intermediate plate mesoderm and the lateral plate mesoderm

Question 43

What happens to the paraxial mesoderm after it is formed ?

Answer 43

Divides into the dermatome, myotome and sclerotome.
The dermatome will migrate and form the dermis of the skin. the myotome will migrate and form the muscles and the sclerotome will migrate and form the bones including the vertebrae.
When they migrate they take there innervation with them. So if something if from the T10 dermatome it means that it migrated form the T10 spinal cord level.