Embryology

Question 1

The pre-embryonic phase of human development occurs between what weeks of development?

Answer 1

0-3

Question 2

The embryonic phase of development occurs between what weeks?

Answer 2

4-8

Question 3

The foetal phase of development occurs between what weeks?

Answer 3

9-40

Question 4

What is produced during Oogenesis?

Answer 4

1 ovum and 3 polar bodies

Question 5

What is produced during spermatogenesis?

Answer 5

4 sperm

Question 6

What is the difference between the genetic material present in sperm and ovum?

Answer 6

All ovum will have 22 chromosomes and an X chromosome, sperm will have 22 chromosomes and an X or Y chromosome

Question 7

Are the products of meiosis genetically identical or genetically unique?

Answer 7

Genetically unique

Question 8

When is a zygote produced?

Answer 8

When the nucleus of a sperm fuses with the nucleus of an ovum

Question 9

Are zygotes haploid or diploid cells?

Answer 9

Diploid

Question 10

How many sperm penetrate the ovum?

Answer 10

One

Question 11

What is the progression between Morula, Blastocyst and Zygote in development?

Answer 11

Zygote -> Morula -> Blastocyst

Question 12

The zygote divides to form a morula, does it divide by meiosis or mitosis?

Answer 12

Mitosis

Question 13

The DNA for the cytoplasm and cytoplasmic organelles comes from which parent?

Answer 13

Mother

Question 14

What is a morula?

Answer 14

A solid ball of cells

Question 15

Mitochondrial diseases are inherited from which parent?

Answer 15

Mother

Question 16

What happens as the number and size of cells in the morula increases?

Answer 16

• Getting nutrition to the central core of cells becomes more difficult
• the blastocyst cavity forms

Question 17

What is the name given to the outer layer of cells surrounding a blastocyst cavity and inner cell mass?

Answer 17

Trophoblast

Question 18

How long does the first cell division take?

Answer 18

36 hours

Question 19

As time progresses, successive cell divisions take

Answer 19

less time

Question 20

Where in the body is the ovum fertilised?

Answer 20

Uterine tube

Question 21

Where in the body does the ovum implant?

Answer 21

Uterine wall

Question 22

How is the ovum transported from the ovary down the uterine tube?

Answer 22

By ciliated epithelium and fimbriae at the end of the uterine tube

Question 23

What causes an ectopic pregnancy?

Answer 23

When the ovum gets stuck in the uterine tube

Question 24

Where does implantation of the ovum occur?

Answer 24

In the uterine endometrial layer

Question 25

During what week does the placenta begin to develop (generally)?

Answer 25

Week 2 (pre-embyronic phase)

Question 26

The trophoblast helps what structures to form?

Answer 26

Sacs, membranes and umbilical cord

Question 27

What is a chorion?

Answer 27

A trophoblast which has divided and joined up with other cells

Question 28

Why is the endometrium a good environment for implantation?

Answer 28

It has a good supply of blood vessels and nutrients

Question 29

What structures of the chorion help the blastocyst to burrow into the endometrium?

Answer 29

Villi

Question 30

What layer of the uterus is the endometrium?

Answer 30

Inner layer

Question 31

After how many days (roughly) does the blastocyst begin to burrow into the uterine wall?

Answer 31

7

Question 32

What is a trophoblast?

Answer 32

The outer lining of cells around the blastocyst cavity

Question 33

Give 3 functions of the chorion

Answer 33

- implantation process - forms part of the placenta - secretes human chorionic gonadotropin

Question 34

What hormone is used to detect pregnancy?

Answer 34

HCG (human chorionic gonadotropin)

Question 35

Once the blastocyst has implanted in the uterus, what is the endometrium in which the blastocyst has implanted known as?

Answer 35

Decidua basalis

Question 36

The inner cell mass is flattened to form what two layers of cells?

Answer 36

Epiblast and hypoblast

Question 37

What is the layered flat disc formed by the epiblast and hypoblast layers known as?

Answer 37

Bilaminar disc

Question 38

What two cavities start to form once the bilaminar disc is formed?

Answer 38

Amniotic cavity and yolk sac

Question 39

What is the allantoic cavity?

Answer 39

Cavity in which the waste products from the embryo are stored

Question 40

What are the main functions of the placenta?

Answer 40

- Foetal nutrition - Transport of waste and gases - Immune

Question 41

What is the surface of the foetal part of the placenta like?

Answer 41

Smooth with foetal blood vessels and end of umbilical cord

Question 42

What is the surface of the maternal part of the placenta?

Answer 42

The decidua basalis

Question 43

At what point in development does the placenta mature?

Answer 43

18-20 weeks

Question 44

What causes fraternal/dizygotic births?

Answer 44

2 different ova released, fertilised by 2 different sperm and forming 2 different zygotes

Question 45

What causes identical/monozygotic births?

Answer 45

1 ovum released, fertilised by 1 sperm, forms 1 zygote which then divides into 2

Question 46

What is Gastrulation?

Answer 46

Formation of germ layers

Question 47

What is Neurulation?

Answer 47

Formation of neural tube

Question 48

Other than Gastrulation and Neurulation, what develops in week three of development?

Answer 48

- somites | - early development of CVS

Question 49

What is the purpose of the axis of the embryo?

Answer 49

Distinguishes between left and right and top and bottom so organs/body structures form in the right place

Question 50

What are the germ layers formed in gastrulation?

Answer 50

- ectoderm - mesoderm - endoderm

Question 51

What germ layer is the inner layer?

Answer 51

Endoderm

Question 52

Once the 3 germ layers are formed, cells are

Answer 52

specialised

Question 53

What is the notochord?

Answer 53

Solid tube of cells which induces the cells of the ectoderm to form the neural tube

Question 54

From what germ layer does the neural plate form?

Answer 54

Ectoderm

Question 55

The neural tube induces the mesoderm to

Answer 55

thicken

Question 56

What 3 parts does the mesoderm separate into?

Answer 56

- paraxial mesoderm - intermediate plate mesoderm - lateral plate mesoderm

Question 57

Lateral plate mesoderm splits to form

Answer 57

a somatic and a splanchnic mesoderm

Question 58

What is the name of the space between the somatic and the splanchnic mesoderm?

Answer 58

Intraembryonic coelom

Question 59

What layer of the mesoderm forms somites?

Answer 59

Paraxial mesoderm

Question 60

What layer of the mesoderm forms the urogenital system?

Answer 60

Intermediate plate mesoderm

Question 61

What layer of the mesoderm forms the body cavities and coverings?

Answer 61

Lateral plate mesoderm

Question 62

From what germ layer is the gut formed?

Answer 62

Endoderm

Question 63

Between what weeks of development is the Organogenetic period?

Answer 63

4-8

Question 64

In what way does an embryo fold so that the ectoderm covers its full surface?

Answer 64

Laterally