Embryology

Question 1

What is morphogenesis?

Answer 1

The process of the cell changing shape

Question 2

Where does fertilisation normally occur?

Answer 2

In the fallopian uterine tube - the ampulla

Question 3

What do endoderm cells become?

Answer 3

Lining of the gastrointestinal tract
Lungs
Liver, pancreas, stomach, intestines, oesophagus

Question 4

What do mesoderm cells become?

Answer 4

Muscles
Skin
Bones
Heart, kidneys, bladder, testies

Question 5

What do ectoderm cells become?

Answer 5

Outer layer of skin
Sweat glands
Hair
Nervous system

Question 6

What is the name of a zygote that has divided into 16 cells?

Answer 6

Morula

Question 7

What is the name given to the process of the zygote mitotically dividing?

Answer 7

Cleavage

Question 8

What is the name of a fertilised egg cell?

Answer 8

Zygote

Question 9

What happens after cleavage to for a blastocyst?

Answer 9

Compaction

Question 10

What is the name of the glycoprotein membrane surrounding the morula?

Answer 10

Zona pellucida

Question 11

What is the cavity in a blastocyst called?

Answer 11

Blastocyst cavity

Question 12

What does cleavage first produce?

Answer 12

2 blastomeres

Question 13

What is the potency of the cells in a morula?

Answer 13

Totipotent - can become any type of cell

Question 14

What is pre-implantation genetic diagnosis?

Answer 14

Used in assisted reproductive technique
Removal of cell from morula
Tested for heritable conditions
Prior to transfer into mother

Question 15

What is the stage after cleavage and the formation of the morula?

Answer 15

Compaction

Question 16

What is the name of the cell after compaction?

Answer 16

Blastocyst

Question 17

What are the inner and outer cell masses of a blastocyst called?

Answer 17

Inner - embryoblast
Outer - trophoblast

Question 18

What is the potency of cells after compaction?

Answer 18

Pluripotent - can become many cells

Question 19

What are the next stages after compaction?

Answer 19

Hatching and implantation

Question 20

What do the trophoblasts differentiate into?

Answer 20

Syncytiotrophoblasts
Cytotrophoblasts

Question 21

What do the embryoblsats differentiate into?

Answer 21

Epiblasts
Hypoblasts
(The bilaminer disk)

Question 22

What week do the epiblasts and trophoblasts differentiate?

Answer 22

Week 2

Question 23

What is the top layer of the epiblast?

Answer 23

Epiblast

Question 24

What is the small cavity within the bilaminer disk?
Which layer?

Answer 24

Amniotic cavity
Epiblast

Question 25

What is the name given to the fused vacuoles in the uterine?

Answer 25

Lacunae

Question 26

What is the name of the larger cavity?

Answer 26

Primitive yolk sac

Question 27

Where is the primitive yolk sac positioned?

Answer 27

Between the hypoblasts and cytotrophoblasts

Question 28

What has to happen for uteroplacental circulation to begin?

Answer 28

Lacuna becomes continuous with the sinusoids (maternal capillaries)

Question 29

What forms the secondary yolk sac?

Answer 29

Primitive yolk sac pinches off

Question 30

What forms the chorionic cavity?

Answer 30

Extraembryonic mesoderm merge

Question 31

What is the embryo suspended by? What will it eventually become?

Answer 31

Connecting stalk Umbilical cord

Question 32

What is the streak in the bilaminer disk call?

Answer 32

Primitive streak

Question 33

What does the bilaminer disk become? What is it made from?

Answer 33

Trilaminer disk Ectoderm Mesoderm Endoderm (Germ layers)

Question 34

What do the mesoderm cells differentiate into?

Answer 34

Notochord cells

Question 35

What forms the neural tube?

Answer 35

The ectoderm folding inwards

Question 36

What is an ectopic pregnancy?

Answer 36

Implantation anywhere other than the uterine body - commonly the Fallopian tubes

Question 37

What is placenta praevia?

Answer 37

Implantation in the lower uterine segment Placenta blocks the cervix Can cause haemorrhage due to the vulnerable blood vessels of the placenta

Question 38

When are 50% zygotes lost?

Answer 38

First 2-3 weeks

Question 39

What comes first neurulation or gastrulation?

Answer 39

Gastrulation

Question 40

When does gastrulation happen?

Answer 40

Third week

Question 41

What does the dermatome become?

Answer 41

Dermis - the skin

Question 42

What does the myotome become?

Answer 42

Muscles

Question 43

What does the sclerotome become?

Answer 43

Bones

Question 44

When does cleavage take place?

Answer 44

Week 1

Question 45

When does implantation take place?

Answer 45

Week 1

Question 46

When does hatching take place?

Answer 46

Week 1

Question 47

When does the bilaminer disk form?

Answer 47

Week 2

Question 48

What happens on day 9?

Answer 48

The yolk sac forms

Question 49

What happens on day 14?

Answer 49

Chorionic cavity is formed

Question 50

When does the secondary yolk sac form?

Answer 50

Day 13

Question 51

What happens on day 12?

Answer 51

Uteroplacental circulation begins

Question 52

What does the notochord become?

Answer 52

The vertebral column - spinal chord

Question 53

What do somites become?

Answer 53

Vertebral column, ribs and extensor muscles of spine

Question 54

What do the somatic layers become?

Answer 54

Diaphragm and limb muscles

Question 55

What forms the muscles of the heart?

Answer 55

Splanchnic layer

Question 56

What is a splanchnic mesoderm?

Answer 56

Overlies the endoderm and is a layer continuous with mesoderm covering the yolk sac

Question 57

What is the somatic mesoderm?

Answer 57

The outer layer formed after the split of the lateral plate mesoderm