lecture 4

Question 1

Blastomere formed after?

Answer 1

first division

Question 2

Rotational cleavage

Answer 2

on orientation- meridionally

at 90 degrees, equatorially

Question 3

Blastula stage?

Answer 3

16-32 blastomeres present

Question 4

morala stage

Answer 4

more than 32 cells

Question 5

Zona pellucida

Answer 5

thin layer of cells which keeps all the blastomeres together in a fluid filled sac.

Question 6

zygote

Answer 6

blastocyst (2 cell layers)

Question 7

Inner cell mass

Answer 7

embryonic stem cells

Question 8

blastocoel?

Answer 8

Cavity which forms the placenta

Question 9

trophoblast

Answer 9

outer cell layer

Question 10

Hatching?

Answer 10

After blastocyst stage no long contained with the zone pellucida

Question 11

What enables hatching to occur?

Answer 11

Enzymes

Question 12

Where does the blastocyst implant itself?

Answer 12

In the uterine horn

Question 13

Structure of mouse uterine horns?

Answer 13

2 ovary
2 oviducts
two uterine horns
vagina

Question 14

Ovary

Answer 14

where eggs are produced

Question 15

oviduct

Answer 15

where the egg is released

Question 16

When released (egg) what happens

Answer 16

moves down the uterine horn

Question 17

Uterus

Answer 17

single structure in which egg impacts it self

Question 18

divisions occur within? human uterus

Answer 18

fallopian tube

Question 19

Key difference between mammalian and other species

Answer 19

nutrient medium needed (not in mammals)

Question 20

bilaminar blastocyst structure

Answer 20

epiblast
hypoplast (primitive endoderm) forms a semi circular structure 

and trophoblast around the outside

Question 21

What forms the primitive yolk sac and amniotic cavity?

Answer 21

Cell movements:

epiblast continues to divide around the inside of the embryo to form the amniotic cavity

Hypoblast migrates to the bottom of the embryo and forms the primitive yolk sac ( which provides nutrients)

tropoblast continues to dive and migrate out of the egg to form the syncytiotrophoblast (extends outwards)
eventually forms the placenta

Question 22

Gastrulation?

Answer 22

Formation of three cell layers

Question 23

Node?

Answer 23

Signalling centre for cell movement/ formation of the primitive groove/streak

Question 24

Where is the node found?

Answer 24

Posterior end of the epiblast layer

Question 25

Gastrulation description

Answer 25

Epiblast cells dissociate and migrate through the primitive groove and node invading and underlying the primitive endoderm cells.

forms three cell layer

cells which have moved through the node come the notochord

Question 26

What cells become the notochord?

Answer 26

Cells which move through the node

Question 27

Germ layers form?

Answer 27

1- ECTODERM- epidermis, brain CNS
2- mesoderm= muscle, kidney, gonads tissues of the heart 
3- Endoderm
epithelium lining (is) 
repertory tract lining 
liver lungs pancreas

Question 28

Notochord

Answer 28

Signalling centre which initiates the formation of the neural plate and groove

Question 29

Neuralation in mice description

Answer 29

Notochords enables this to occur 
-neutral plate forms 
-neural groove and fold
-cells move towards eachother 
- cells on the outside stick back up and dissociation 
will become the spine

Question 30

Inner cell mass made cup of?

Answer 30

Epiblast and primitive endoderm (blastocyst)

Question 31

cell fate

Answer 31

what a cell will become in the future

Question 32

Differentiation

Answer 32

process of unspecialised cells becoming specialised

Question 33

Lineage restriction

Answer 33

A cell will only give rise to a particular cell type

Question 34

Genetic screen on a mouse?

Answer 34

No, as we need a large bank of mutatnts, small organisms, cheap and easy to maintain. Mouse doesn’t really fit this requirement

Question 35

embryology on mice ?

Answer 35

no

• mice embryos can’t develop externally
• big embryos needed (mice are small)

Question 36

Transgenic mice?

Answer 36

Removal or addition of a gene

Question 37

Reverse genetics

Answer 37

Have gene which we are interested in, mutagenesis, see the result on the offspring (stable transfection)

Question 38

Method for over-expressing a gene product in mice

Answer 38

1- Take zygote and inject DNA into a plasmid (use a hairpin pipette) male pronuclei used as its larger
2- DNA integrated into pronuclei
3- addition of DNA polymerase promotors etc
insert into surrogate mother
4- Marker eg fluorescent or coat clouds

Question 39

How do they remove the zygote from the mother?

Answer 39

small slit made in mothers back , into uterine Horne

Question 40

Targeted gene knock out?

Answer 40

Homologous recombination using a targeting vector

Question 41

Method for targeting vector?

Answer 41

Obtain embryonic stem cell, make a targeting vector, GE embryonic stem cells with targeting vector. Electrical current used to induce homologous recombination. Which stops mRNA production and therefore expression

Question 42

Type of cells needed for removing a gene of interest

Answer 42

Inner cell mass- embryonic stem cells

Question 43

F2 generation with chimeric pups F1 ?

Answer 43

back cross with a brown mouse to form a fully brown mouse = fully transgenic (all cells have been successfully transfects)

Question 44

chimeric pup

Answer 44

brown and black

Question 45

What type of injection used to inject es into host blastocyst?

Answer 45

Micro-injection

Question 46

NOBEL PRIZE FOR THIS WORK? -specific gene modifications in mice.

Answer 46

Mario, martin evans, oliver smithies

Question 47

Pdx1 example?

Answer 47

• Pdx1- transcription factor
• controls pancreas development
• Knock out has no pancreas and was found to be smaller

Question 48

genetic screen is what type of genetics?

Answer 48

forward genetic (genetic scree)

• generate mutation
• find phenotype
• and locate that gene

Question 49

mouse knock out is what kind of genetics

Answer 49

reverse genetics
start with gene
make knockout
look at phenotype