Lecture 6 Flashcards
what are the 5 processes that building an embryo involves?
1) cleavage - division without increase in cell mass
2) pattern formation - spatio-termporal pattern
3) morphogenesis - major 3D changes
4) growth
5) cell differentiation - cells become structurally and functionally different
what is a post implantation epiblast?
structure implanted into uterus wall which then undergoes morphological changes/ movement differentiation to generate the 3 germ layers
in early mouse development what 4 things happen after the 8 cell stage?
1) the embryo compacts
2) forms tied junctions between cells
3) changes the cell surface membrane
4) polarisation takes place
what happens in the 16 cell stage?
definite inside cells and outside cells
what is the Trophectoderm and where is it derived from?
it is derived from outer cells and gives placental tissue
what does the inner cell mass make and what ends up on the outside and middle?
the embryo - primitive endoderm cells end up on the outside and epiblast cells end up in the middle
what is the process of gastrulation?
produces 3 germ layers - ectoderm, mesoderm, endoderm
what is the function of the primitive streak?
cells change from ectodermal cells into endoderm and mesoderm when they migrate through
what is key to the patterning of the 3 germ layers?
signalling
what are the 4 main signalling centres?
1) epiblast
2) AVE
3) extra embryonic endoderm
4) the node
what is a key point which happens to the proximal epiblast?
it is shifted to the posterior of the embryo
what does the hensons node eventually turn into?
the notochord , neural tube, somites etc
how does the embryology relate to differentiation of pluripotent stem cells?
you have to mimic the timing, concentration and position of these signals
what forms the spinal chord and brain?
the neural tube
what do the neural crest cells give rise to?
the internal nervous system
why is dorsal/ventral patterning important?
because the types of neurones which form in the spinal cord differ depending on if they are in the front or back of the embryo
describe spatial axes used in pre-implantation epiblasts
abembryonic - furthest away from the cell mass
embryonic - side of the cell mass
in early mouse development what do the outer cells and inner cells make?
inner cells —> epiblast (3 germ layers) –> embryo
outer cells –> extra embryonic (placenta)
what do the epiblast cells become?
the ectoderm layer
what is the hypoblast?
extra embryonic endoblast which gets displaced as cells pass through the primitive streak and migrate to from either mesoderm or endoderm
what affect does signalling from the visceral endoderm have on the proximal epiblast?
effects where the primitive streak will form in the endoderm - signals drive the proximal epiblast to shift to posterior side of embryo
what signals must be restricted to the posterior end of the epiblast if you want tissues derived from the primitive streak?
WNT and TGFbeta - without these signals = ectoderm
what signals are needed in an embryonic stem cell to make the primitive streak and ectoderm?
primitive streak = WNT and TGFb
ectoderm = block TGFb and BMP
describe the signals needed for ectodermal patterning
FGFs for proliferaition
BMP - decides what sort of ectoderm (axes)
what drives neural differentiation in ES cells?
FGF with no BMP added
