Flashcards in Embryology: developmental processes Deck (29)
what is the first differentiation event?
what is the driving force behind the first lineage restriction?
what are the two domains of polarisation?
what part of the blastocyst becomes polar and what does not?
Trophoblast cells become polarised, while the Inner Cell Mass cells lack apical/basal polarity
what is polarisation?
formation of apical complex
what is asymmetric cell divison?
segregation of apical complex
what is cell position?
suppression of apical complex in inner cells
what is cell fate?
restricted expression of lineage specific genes
what are signalling centres?
what does the node/organiser do?
Produces signalling molecules that direct the development of surrounding tissues
what can transplants of node/organiser induce?
the formation of a second body axis and neural tube
where are organisers found?
all vertebrate embryos
what happens when the primitive node swelling produces signals?
signal diffuses away and encounters other cells, those cells will respond to signal in specific way, this response will be different between cells types i.e one signal has a range of effects
Describe the signalling gradients.
Positional information: cells respond in a specific way depending on the concentration of the signalling molecule
what does signalling gradients regulate?
Differentiation in the Neural Tube by providing Positional Information
what does noto cord produce?
signal molecule sonic hedgehog will diffuse up through neural tube
where does BMP's signal molecule diffuse?
dorsal regions forwards
what is it called when there is equal number of sonic and BMP signals?
what does programmed cell death help?
shape the embryo
How are digits of feet and hands formed?
BMP4 signalling triggers cell death programme in the interdigital zones of foot and hand plate
what do localised changes in shape during neurulation lead to?
folding of the neural plate at median and doors-lateral hinge points
where does tissue fusion occur?
the edges of the neural plate are brought together
what is tissue fusion also required for?
formation of the face
how are structures of the face formed?
5 facial swellings fuse
describe cell migration.
Movement of cells from one location to another is a frequent event during development:
Describe the epithelial to mesenchymal transition (EMT).
Epithelial Cell State: cells arranged in a sheet with specialised membrane contacts; adherens and tight junctions
Mesenchymal Cell State: loosely associated, often motile cells with only transient focal attachements to other cells
what are transitions between these states required for?
> Neural Crest
> Cardiac Valves
> Secondary Palate formation
what are E-Cadherins?
the ‘caretaker’ of the epithelial cell state