Lecture 6

Question 1

what are the 5 processes that building an embryo involves?

Answer 1

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

Question 2

what is a post implantation epiblast?

Answer 2

structure implanted into uterus wall which then undergoes morphological changes/ movement differentiation to generate the 3 germ layers

Question 3

in early mouse development what 4 things happen after the 8 cell stage?

Answer 3

1) the embryo compacts
2) forms tied junctions between cells
3) changes the cell surface membrane
4) polarisation takes place

Question 4

what happens in the 16 cell stage?

Answer 4

definite inside cells and outside cells

Question 5

what is the Trophectoderm and where is it derived from?

Answer 5

it is derived from outer cells and gives placental tissue

Question 6

what does the inner cell mass make and what ends up on the outside and middle?

Answer 6

the embryo - primitive endoderm cells end up on the outside and epiblast cells end up in the middle

Question 7

what is the process of gastrulation?

Answer 7

produces 3 germ layers - ectoderm, mesoderm, endoderm

Question 8

what is the function of the primitive streak?

Answer 8

cells change from ectodermal cells into endoderm and mesoderm when they migrate through

Question 9

what is key to the patterning of the 3 germ layers?

Answer 9

signalling

Question 10

what are the 4 main signalling centres?

Answer 10

1) epiblast
2) AVE
3) extra embryonic endoderm
4) the node

Question 11

what is a key point which happens to the proximal epiblast?

Answer 11

it is shifted to the posterior of the embryo

Question 12

what does the hensons node eventually turn into?

Answer 12

the notochord , neural tube, somites etc

Question 13

how does the embryology relate to differentiation of pluripotent stem cells?

Answer 13

you have to mimic the timing, concentration and position of these signals

Question 14

what forms the spinal chord and brain?

Answer 14

the neural tube

Question 15

what do the neural crest cells give rise to?

Answer 15

the internal nervous system

Question 16

why is dorsal/ventral patterning important?

Answer 16

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

Question 17

describe spatial axes used in pre-implantation epiblasts

Answer 17

abembryonic - furthest away from the cell mass

embryonic - side of the cell mass

Question 18

in early mouse development what do the outer cells and inner cells make?

Answer 18

inner cells —> epiblast (3 germ layers) –> embryo

outer cells –> extra embryonic (placenta)

Question 19

what do the epiblast cells become?

Answer 19

the ectoderm layer

Question 20

what is the hypoblast?

Answer 20

extra embryonic endoblast which gets displaced as cells pass through the primitive streak and migrate to from either mesoderm or endoderm

Question 21

what affect does signalling from the visceral endoderm have on the proximal epiblast?

Answer 21

effects where the primitive streak will form in the endoderm - signals drive the proximal epiblast to shift to posterior side of embryo

Question 22

what signals must be restricted to the posterior end of the epiblast if you want tissues derived from the primitive streak?

Answer 22

WNT and TGFbeta - without these signals = ectoderm

Question 23

what signals are needed in an embryonic stem cell to make the primitive streak and ectoderm?

Answer 23

primitive streak = WNT and TGFb

ectoderm = block TGFb and BMP

Question 24

describe the signals needed for ectodermal patterning

Answer 24

FGFs for proliferaition

BMP - decides what sort of ectoderm (axes)

Question 25

what drives neural differentiation in ES cells?

Answer 25

FGF with no BMP added