Lecture 1

Question 1

What changes are seen in the nervous system of organisms as they increase in complexity

Answer 1

The nervous system increases in complexity too. Axons and neurons become aggregated and there is an increase in hierarchical organisation and integration

Question 2

What is the neural plate and how does it form

Answer 2

The neural plate is a single layered neuroepithelium that is induced from ectoderm on the dorsal side of the embryo that will give rise to the entire nervous system

Question 3

What broad term describes the cells that surround the neural plate

Answer 3

Neurectoderm

Question 4

Complete the diagram below that outlines the two fates of ectoderm during the formation of the neural plate?

Answer 4

See completed diagram

Question 5

Give an example of a transcription factor which causes the organiser/node to begin expressing BMP antagonists

Answer 5

Goosecoid

Question 6

What is the overall effect of the synthesis and secretion of BMP antagonists from the organiser

Answer 6

The BMP antagonists prevents adjacent cells from receiving the BMP signal and hence form neural plate

Question 7

What sort of movements does the organiser/node undergo to form the axial mesoderm

Answer 7

Involution intercalation and convergent extension

Question 8

What are the three tissues that the node/organiser gives rise to

Answer 8

Anterior prechordal mesendoderm prechordal endoderm and notochord

Question 9

Match up these cell movements with their definitions

Answer 9

A – III B – IV C – VI D – I E – II and F - V

Question 10

The entire axial mesoderm lies beneath the forebrain T or F

Answer 10

F – the prechordal mesoderm and anterior prechordal mesendoderm lie beneath the forebrain whereas the notochord lies beneath the midbrain hindbrain and spinal cord

Question 11

Explain why is it that the early induced neural plate is said to be anterior in character

Answer 11

Neural plate is expressing markers that are later confined to the forebrain (telencephalon and diencephalon). This is because BMP antagonists induce neural tissue that has anterior identity

Question 12

BMP antagonists and Wnt antagonists are maintained anteriorly in the PM T or F

Answer 12

T

Question 13

Which signals are expressed posteriorly by the late organiser/node

Answer 13

FGF Wnts and RA

Question 14

What is the name of the structure that forms at the edge of the neural plate and ectoderm

Answer 14

Neural crest

Question 15

Which cells migrate laterally and give rise to the peripheral and enteric nervous system

Answer 15

Neural crest cells

Question 16

What happens to the cells in the dorsal neural tube that don’t migrate laterally and give rise to the peripheral and enteric nervous system

Answer 16

They are retained and form the roof plate

Question 17

Give an example of a transcription factor induced by BMPs in the neural plate border cells which direct a dorsal cell fate adoption

Answer 17

Msx

Question 18

Briefly describe how the neural tube is ventralised posteriorly

Answer 18

The secreted ligand Sonic hedgehog (Shh) is expressed in notochord and then in floor plate. Shh acts as a morphogen to induce different progenitor cells along the dorso-ventral axis of the future spinal cord. Different transcription factors are induced in bands of progenitor cells along the dorsoventral axis. These are readouts of a Shh morphogen gradient along D-V axis. The transcription factor code dictates later differentiation of the neurons which then move laterally