Early mouse development - lecture 11 Flashcards
What are the first four stages of a mouse development
- blastomeres , blastula , morula , blastocyst
what is rotational cleavage?
Can be an odd number of blastomeres at certain times
When does hatching occur?
At the blastocyst stage , secretes enzymes which break down the zona pellucida
What is the blastocyst made up of?
Inner cell mass surrounded by trophoblast cells and contains a fluid filled cavity called a blastocoel
What happens prior to implantation, to inner cell mass?
Formation of two layers; the epiblast and the hypoblast (primitive endoderm)
What is the role of the hypoblast (primitive endoderm)?
lines the blastocoel forming the yolk sac.
What is the role of the epiblast?
forms the amniotic cavity
What is the role of the trophoblast?
continue to divide to invade the uterus forming the syncytiotrophoblast
What does the posterior node of the epiblast signal?
signals for a primitive streak to form which then forms a groove
What happens to the epiblast cells during gastrulation?
Migrate through the primitive groove , invading endoderm cells.
What happens after this process of ingression?
formation of 3 germ layers, ectoderm, mesoder and endoderm. The cells which have moved through the node , will form the notochord
What is a notochord?
a cartilaginous skeletal rod supporting the body
What does the ectoderm develop into?
- epidermis
- brain , CNS
What does the mesoderm develop into?
- muscle , connective tissues , bone
- kidney and gonads
- tissues of the heart
What does the endoderm develop into?
- epithelium lining of the gastrointestinal tract
- epithelium lining of respiratory tract
- liver, lungs , pancreas
How to add a gene into a mouse
- 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
What is the procedure to make a targeted knockout mouse?
- 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
Who won the Nobel prize for targeted mouse knockouts?
- Sir Martin Evans
- Mario Capecchi
- Oliver Smithies
What happens when you knock out the Pdx1 gene?
no pancreas development
How do you make a targeting construct?
- 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
