Embryology: developmental processes

Question 1

what is the first differentiation event?

Answer 1

blastocyst forming

Question 2

what is the driving force behind the first lineage restriction?

Answer 2

polarisation

Question 3

what are the two domains of polarisation?

Answer 3

• apical domain

- basolateral domain

Question 4

what part of the blastocyst becomes polar and what does not?

Answer 4

Trophoblast cells become polarised, while the Inner Cell Mass cells lack apical/basal polarity

Question 5

what is polarisation?

Answer 5

formation of apical complex

Question 6

what is asymmetric cell divison?

Answer 6

segregation of apical complex

Question 7

what is cell position?

Answer 7

suppression of apical complex in inner cells

Question 8

what is cell fate?

Answer 8

restricted expression of lineage specific genes

Question 9

what are signalling centres?

Answer 9

the node/organiser

Question 10

what does the node/organiser do?

Answer 10

Produces signalling molecules that direct the development of surrounding tissues

Question 11

what can transplants of node/organiser induce?

Answer 11

the formation of a second body axis and neural tube

Question 12

where are organisers found?

Answer 12

all vertebrate embryos

Question 13

what happens when the primitive node swelling produces signals?

Answer 13

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

Question 14

Describe the signalling gradients.

Answer 14

Positional information: cells respond in a specific way depending on the concentration of the signalling molecule

Question 15

what does signalling gradients regulate?

Answer 15

Differentiation in the Neural Tube by providing Positional Information

Question 16

what does noto cord produce?

Answer 16

signal molecule sonic hedgehog will diffuse up through neural tube

Question 17

where does BMP’s signal molecule diffuse?

Answer 17

dorsal regions forwards

Question 18

what is it called when there is equal number of sonic and BMP signals?

Answer 18

interneurons

Question 19

what does programmed cell death help?

Answer 19

shape the embryo

Question 20

How are digits of feet and hands formed?

Answer 20

BMP4 signalling triggers cell death programme in the interdigital zones of foot and hand plate

Question 21

what do localised changes in shape during neurulation lead to?

Answer 21

folding of the neural plate at median and doors-lateral hinge points

Question 22

where does tissue fusion occur?

Answer 22

the edges of the neural plate are brought together

Question 23

what is tissue fusion also required for?

Answer 23

formation of the face

Question 24

how are structures of the face formed?

Answer 24

5 facial swellings fuse

Question 25

describe cell migration.

Answer 25

Movement of cells from one location to another is a frequent event during development:

• Gastrulation
• Neural Crest
• Germ Cells
• Interneurons

Question 26

Describe the epithelial to mesenchymal transition (EMT).

Answer 26

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

Question 27

what are transitions between these states required for?

Answer 27

> Gastrulation
Neural Crest
Cardiac Valves
Secondary Palate formation

Question 28

what are E-Cadherins?

Answer 28

the ‘caretaker’ of the epithelial cell state

Question 29

what are 90% of oral cancers characterised by?

Answer 29

low E-Cadherin expression.

Salvia appears to provide a good environment for metastasis