Embry, Gastrulation Flashcards
What is the function of the second polar body?
Set up anterior-posterior axis and marks the axis of first cleavage.
When is the left-right axis set up?
Following gastrulation
When is the ventral-dorsal axis set up?
After the anterior-posterior axis is.
What does delamination of the inner cell mass produce?
The bilaminar germ disk (epiblast and hypoblast)
What are the two layers of the bilaminar disk?
Epiblast- embryo proper
Hypoblast- underneath the epiblast
When is the bilaminar disk formed?
Day 8
What tissues does the ectoderm form?
Epidermis, les, retina, internal ear, CNS, middle and posterior pituitary and pineal gland.
What tissues does the mesoderm form?
Muscle, connective tissue, dermis, circulatory system, kidney, uterus, gonads
What tissues does the endoderm form?
Midgut, bladder, lungs, liver, pancreas, thyroid, thymus, anterior pituitary
Which layer of the bilaminar disks undergoes gastrulation?
Epiblast
When does gastrulation occur?
Soon after implantation, 14-16 days.
When is the primitive streak clearly visible?
15-16 days
Is the primitive node near the anterior or posterior end?
Anterior
Abnormalities in which layer give rise to caudal dysgenesis?
Mesoderm
Disruption is which two genes in mice gives rise to caudal dysgenesis?
Brachyury, Wnt, engrailed
When does gastrulation occur?
Week 2
What organism has been used to study gastrulation?
Urchin, chicken
When does gastrulation occur in chickens?
Within 5 hours of laying
When is there full formation of all three germ layers?
Day 16
When does germ layer formation occur?
Days 6-19
What are the two major components of germ later formation?
Delamination and gastrulation
How is the left-right axis establish?
Nodal cilia direct flow of fluid with signalling molecules to the left.
What is the protein involved in left-right axis establishment by the node cilia?
Left-right dynein.
What growth factors are involved in left-right axis establishment?
Shh and FGF8
What is the effect of transplanting a node from one salamander to another salamander?
Another embryo body will form.
What is the effect of transplanting a node from one chick to another chick?
Some important structures such as the neural tube will form.
