Embryology Development II

Question 1

What is gastrulation ?

Answer 1

Establishment of the three embryonic germ layers

Question 2

What is the function of the of the 3 germ layers?

Answer 2

Layers from which all tissues of the body originate from

Question 3

When is the embryonic period?

Answer 3

3-8 weeks after fertilisation

Question 4

What is teratogenesis ?

Answer 4

Process by which congenital malformations are produced in an embryo/foetus

Question 5

When is there the greatest risk of teratogenesis ?

Answer 5

During the embryonic period

Weeks 3-8 after fertilisation

Question 6

Give some examples of teratogens ?

Answer 6

• warfarin
• isotretinon
• valproate acid
• thalidomide

Question 7

Which virus can lead to teratogenesis ?

Answer 7

Rubella

Question 8

What surface of the epiblast is the primitive streak formed?

Answer 8

Dorsal

Question 9

Which week is the primitive streak formed?

Answer 9

Week 3 after fertilisation

Question 10

How many days after fertilisation is the primitive streak formed ?

Answer 10

15-17 days

Question 11

What is the name of the important structure that is formed in week 3 on the epiblast ?

Answer 11

Primitive streak

Question 12

At the start of gastrulation how many layers are there and what are they called ?

Answer 12

2
Epiblast
Hypoblast

Question 13

From which layer of the bilaminar disk is the trilaminar disk formed?

Answer 13

Epiblast

Question 14

What are the name of the layers formed at the end of gastrulation ?

Answer 14

Ectoderm
Mesoderm
Endoderm

Question 15

What is derived from the ectoderm ?

Answer 15

Epidermis

Nervous system

Question 16

What is derived from the mesoderm ?

Answer 16

Muscle 
Cartilage 
Bone 
Heart 
Blood vessels

Question 17

What is derived from the endoderm?

Answer 17

Epithelial lining of GI tract
Respiratory tract
Parenchyma of glands

Question 18

What is situs inversus?

Answer 18

Heart and other organs develop on the wrong side of the body

Question 19

What side of the body is the stomach and spleen on ?

Answer 19

Left

Question 20

How many lobes does the left lung have?

Answer 20

2

Question 21

How many lobes does the right lobe have?

Answer 21

3

Question 22

Where on the primitive streak is the control centre for gastrulation ?

Which type of cells here determine what side organs grow?

Answer 22

Primitive node

Ciliated cells

Question 23

When does gastrulation take place ?

Answer 23

3rd week of development.

Question 24

What is neurulation ?

Answer 24

Development of CNS during embryonic period

Question 25

When does neurulation occur?

Answer 25

Week 4

Question 26

Which group of cells sends signals for neurulation ? Where is this structure? Where does it send signals too?

Answer 26

Notochord Mesoderm Ectoderm

Question 27

What are somites?

Answer 27

Body segments

Question 28

When in development does the first somite appear?

Answer 28

Day 20

Question 29

Where does the first somite appear ?

Answer 29

Occipital region

Question 30

At the end of week 5 how many pairs of somites are formed?

Answer 30

42-44

Question 31

How many somites are there in humans ?

Answer 31

31 pairs

Question 32

What are the 3 somite derivatives?

Answer 32

- dermatome - myotome - sclerotome

Question 33

What is sclerotome a pre cursor of?

Answer 33

Bone

Question 34

What is the buccopharyngeal membrane ?

Answer 34

Area of trilaminar disc with no mesoderm. | Area that ruptures to give opening of oral cavity

Question 35

What are the 2 stages of folding of the embryo in week 4?

Answer 35

- cephalocaudal folding | - Lateral folding

Question 36

What causes cephalocaudal folding to happen?

Answer 36

Growth of the neural tube

Question 37

What causes lateral folding to occur?

Answer 37

Growth of the somites

Question 38

Which type of folding happens in the saggital plane ?

Answer 38

Cephalocaudal

Question 39

Which type of folding happens in the transverse plane?

Answer 39

Lateral

Question 40

In which week of embryonic development does folding occur?

Answer 40

4th