Lect. 13 - nervous system induction Flashcards
(18 cards)
primitive nodes’ role in forming notochord
provides source of cells that will form the notochord
Describe formation of the notochord
cell precursors migrate anteriorly and then left behind as rodlike aggregation as primitive streak regresses; notochordal cells fuse w/ flanking endodermal cells and from a canal; the cells separate and aggregate to form notochord
what is the relationship of Nodal to the establishment of the anteroposterior axis
expression of nodal in post. epiblast and blocking of nodal in anterior epiblast (by lefty 1 and cer 1) results in the establishment of the axis
how is wnt3 related to nodal?
Wnt3 induces the expression of nodal
what signaling molecules are involved in the inhibition of posterior structures?
cerebrus-like and DKK-1
what signaling molecules from the primitive node are involved in neural induction?
noggin and chordin
nodal is a signaling molecules produced by the primitive node; what is its role in the induction?
it induces the primitive streak and helps establish left-right symmetry
what is the source and role of Cerebrus-like and DKK-1 in development of ant.-post. axis?
anterior visceral endoderm; inhibits development of posterior structures
what are the origin and effects of TFs goosecoid and brachyury w/ regard to the early primitive streak?
goosecoid: primitive node -activates chordin and noggin
brachyury: primitive streak - notochord fomation; normal movements of cells through primitive streak
what genes are targeted by goosecoid?
chordin and noggin
what are the effects of Foxa-2 on the early primitive streak stage?
establishment of the primitive node; initiates notochord function; establishes midline strucutres cranial to node
in the late primitive streak stage, what signaling molecules is necessary for normal head fromation?
cerebrus-related 1
in the late primitve streak stage, what signaling molecules are needed for neural induction, and what is their origin?
noggin, chordin, and shh; origin: notochord
determination
a process by which a cell or part of an embryo becomes restricted to a given developmental pathway. The point at which a cell becomes committed to a specific cell line.
differentiation:
a complex of changes involved in the progressive specialization of structure and function; often resulting in the formation of luxury molecules
what is the first sign of asymmetry in early development?
the beating of cilia around the primitive node which results in a directional current and expression of TGF-beta molecules
what role does nodal play in asymmetry?
swept to left side of node; stimulates multiple gene expression pathways via Pitx-2
what role does lefty-1 play in asymmetry?
expressed on left side; blocks diffusion of molecules to the right side.
