generating asymmetry Flashcards
1
Q
asymmetry
A
- established during egg formation and early development
- differential cell fates and body axis formation
2
Q
chicken primitive streak induction
A
- posterior marginal zone forms primitive streak
3
Q
organizer and neural induction
A
- node is organizer
4
Q
breaking symmetry and axis formation in frog
A
- organizer and neural induction:
dorsal lip graft produces entire embryo - determinants are localized asymmetrically in the egg
- cortical rotation due to sperm entry , is a translocation of the egg cortex relative to cytoplasm… occurs at fert
- shift causes a change in the symmetry (Dsh is rotated)
5
Q
draw the cortical rotation / role of Dsh
A
–
6
Q
draw the formation of the organizer
A
–
7
Q
organizer role
A
- molecules are secreted from the organizer
- the molecules assist in organizing the embryo, such as pattern formation
ex: BMP antagonists to help with neural development
8
Q
BMP antagonist
A
- noggin chordin DAN/cerberus
9
Q
Wnt antagonists
A
- dicckopf
- cerberus
10
Q
Nodal antagonists
A
- left1
- cerberus-like
11
Q
draw how initial pattern formation of AP and DV axis occurs
A
- gradients of wnts and bmps
– figure
12
Q
compare frog and chicken gradients
A
- figure
13
Q
mammal AP axis… PMZ to 2 signaling centers steps
A
- 1) formation of bilaminar embryo and posterior marginal zone
- 2) two signaling centers develop
14
Q
step 1 of mammalian AP axis
A
- bilaminar disc and posterior marginal zone form primitive streak
bilaminar: epiblast and hypoblast (PrE) - primitive streak forms
15
Q
step 2 of mammalian AP axis
A
- generation of two signaling centers
- original symmetry is broken by displacement of future anterior visceral endoderm to anterior side of the embryonic disk (endo replacing hypo)
- forms signaling centers : anterior and posterior
