Early mouse development - lecture 11

Question 1

What are the first four stages of a mouse development

Answer 1

• blastomeres , blastula , morula , blastocyst

Question 2

what is rotational cleavage?

Answer 2

Can be an odd number of blastomeres at certain times

Question 3

When does hatching occur?

Answer 3

At the blastocyst stage , secretes enzymes which break down the zona pellucida

Question 4

What is the blastocyst made up of?

Answer 4

Inner cell mass surrounded by trophoblast cells and contains a fluid filled cavity called a blastocoel

Question 5

What happens prior to implantation, to inner cell mass?

Answer 5

Formation of two layers; the epiblast and the hypoblast (primitive endoderm)

Question 6

What is the role of the hypoblast (primitive endoderm)?

Answer 6

lines the blastocoel forming the yolk sac.

Question 7

What is the role of the epiblast?

Answer 7

forms the amniotic cavity

Question 8

What is the role of the trophoblast?

Answer 8

continue to divide to invade the uterus forming the syncytiotrophoblast

Question 9

What does the posterior node of the epiblast signal?

Answer 9

signals for a primitive streak to form which then forms a groove

Question 10

What happens to the epiblast cells during gastrulation?

Answer 10

Migrate through the primitive groove , invading endoderm cells.

Question 11

What happens after this process of ingression?

Answer 11

formation of 3 germ layers, ectoderm, mesoder and endoderm. The cells which have moved through the node , will form the notochord

Question 12

What is a notochord?

Answer 12

a cartilaginous skeletal rod supporting the body

Question 13

What does the ectoderm develop into?

Answer 13

• epidermis

- brain , CNS

Question 14

What does the mesoderm develop into?

Answer 14

• muscle , connective tissues , bone
• kidney and gonads
• tissues of the heart

Question 15

What does the endoderm develop into?

Answer 15

• epithelium lining of the gastrointestinal tract
• epithelium lining of respiratory tract
• liver, lungs , pancreas

Question 16

How to add a gene into a mouse

Answer 16

• injection of DNA into pronuclei by micropipette after fertilisation
• DNA integrates into the chromosome
• implant egg in to surrogate oviduct
• determine if gene is taken up via GFP. or screened by PCR reaction

Question 17

What is the procedure to make a targeted knockout mouse?

Answer 17

• obtain ES cells
• Make a targeting construct
• Genetically modify ES cells , by inserting the targeting vector
• inject new ES cells into blastocyst
• implant recombinant embryo into surrogate
• breed pups

Question 18

Who won the Nobel prize for targeted mouse knockouts?

Answer 18

• Sir Martin Evans
• Mario Capecchi
• Oliver Smithies

Question 19

What happens when you knock out the Pdx1 gene?

Answer 19

no pancreas development

Question 20

How do you make a targeting construct?

Answer 20

• Linearized DNA construct is added to ES cell with an electric current.
• DNA construct moves into the nucleus where homologous recombination can take place.
• Recombination can occur and gene of interest is knocked out