Embryology - 1st Lecture

Question 1

What is fertilisation?

Answer 1

A single fertilised egg that fuses 2 nuclei to form a zygote

Question 2

What period is the first 8 weeks of development known as?

Answer 2

Embryonic period

Question 3

What occurs at the end of week 3?

Answer 3

Fertilisation

Question 4

What occurs between weeks 4 and 8?

Answer 4

Embryonic development

Question 5

What occurs between week 9 and birth?

Answer 5

A foetus develops and matures

Question 6

What is gametogenesis?

Answer 6

The creation of gametes (oocyte and spermatozoa)

Question 7

What is cleavage?

Answer 7

A period of rapid cell division to form the morula and then the blastocyst

Question 8

Where does cleavage occur?

Answer 8

In the coat of the oocyte

Question 9

What is a morula? (googles definition)

Answer 9

16 cells (a solid ball of cells resulting from division of a fertilised ovum, and from which a blastocyst is formed)

Question 10

What is a blastocyst?

Answer 10

More than 16 cells; a further development of a morula that implants into uterine wall

Question 11

How many layers does a blastocyst have?

Answer 11

2; one on the inside and one on the outside

Question 12

Over how many days does the formation of the blastocyst occur?

Answer 12

4 days

Question 13

What is gastrulation?

Answer 13

The formation of the germ layers

Question 14

What week of development does gastrulation occur?

Answer 14

Week 3

Question 15

Name the 3 germ layers

Answer 15

Endoderm, ectoderm, mesoderm

Question 16

What else occurs during gastrulation?

Answer 16

The body axes are establishes

Question 17

How does the formation of the body plan come about?

Answer 17

Due to embryonic folding (tube-within-a-tube)

Question 18

What week does the formation of the body plan occur?

Answer 18

Week 4

Question 19

What 2 tubes are involved in embryonic folding in establishing the body plan?

Answer 19

Gut tube and skin/body wall

Question 20

What is organogenesis?

Answer 20

The formation of organs and organ systems

Question 21

Describe what occurs during the foetal period

Answer 21

Growth and weight gain; tissues mature and become function; overt sexual differentiation; ossification; connections are made in the CNS

Question 22

Describe early stage abnormalities

Answer 22

Easily overcome/very rare as embryo can solve problem early or loss of embryo

Question 23

Describe embryonic stage abnormalities

Answer 23

More common as more division occurs so something can be missed

Question 24

Describe foetal stage abnormalities

Answer 24

Abnormalities of the function of organs rather than the development of organs

Question 25

List the 4 primary processes (1)

Answer 25

Cell division; differentitiation; cell attachment; apoptosis

Question 26

Describe differentiation as a primary process

Answer 26

There is specialisation and change in appearance as well as adoption of new functions

Question 27

Describe cell attachment as a primary process

Answer 27

Physical/functional linkages are created and there is the formation of tissues

Question 28

Describe apoptosis as a primary process

Answer 28

Removes cells that have served their function in a controlled way and interwebbing between cells is removed

Question 29

Name the 2 primary processes (2)

Answer 29

Induction; cell migration

Question 30

Describe induction as a primary process

Answer 30

The ability of one cell type to cause another to differentiate by responding to a signal depending on where they are

Question 31

Describe cell migration as a primary process

Answer 31

Movement of cells from one location to another

Question 32

List the 3 secondary processes

Answer 32

Axis formation/polarity; folding/rotation; increase/decrease in mass

Question 33

Describe axis formation/polarity as a secondary process

Answer 33

Allows cells to understand where they are relative to the body axis

Question 34

Describe folding/rotation as a secondary process

Answer 34

Entire embryo or structures within it fold - important in the folding of the heart

Question 35

Describe increase/decrease in mass as a secondary process

Answer 35

Mass either compacts or expands

Question 36

Describe hypertrophy

Answer 36

Individual cells get larger resulting in a larger structure

Question 37

Describe hyperplasia

Answer 37

Increase in size due to increase in number of cells

Question 38

What does the sperm contribute to the zygote?

Answer 38

Only DNA

Question 39

What does the oocyte contribute to the zygote?

Answer 39

Cytoplasm, DNA, protein, rRNA

Question 40

What drives development?

Answer 40

Maternal rRNA

Question 41

What takes over the regulatory site?

Answer 41

The embryo once it begins transcribing its own genes

Question 42

Describe genetic imprinting?

Answer 42

During gametogenesis, DNA has a pattern of methylation which means it is packaged in a specific way so certain genes are exposed, depends on maternal or parental contribution to see what genes are exposed

Question 43

How are Angleman Syndrome and Prader-Willi Syndrome different?

Answer 43

The same region of chromosome is deleted but they differ depending on whether it is a paternal or maternal chromosome that has been cut