Lecture 3

Question 1

Neural Plate

Answer 1

an ectodermal layer of cells - only 1 cell thick - formed immediately from neural induction.

Question 2

Neurulation

Answer 2

Neural plate rolls into the neural tube - growing & elongating along the A-P axis.

Question 3

Identifying neurulation

Answer 3

Obvious shape morphologically

Can also look for expression of Sox2 proteins: which are markers for neural stem cells

Question 4

Neurulation is Heavily Linked to Gastrulation:
Key facts of gastrulation

Answer 4

• embryo transforms from a single-layer of cells into a 3D structure with a recognisable body plan.

Germ layers also assume their final positions - with the axes becoming obvious.

Question 5

Which Transcription Factors are responsible for the Organiser cells & their BMP antagonists?

Answer 5

Siamois & Gsc.

These TF’s transcriptionally activate many genes.

Some encoding factors working intrinsically…
including within the organiser cells.

Question 6

The genes activated by Siamois & Gsc initiate a next step in the organiser cells, what is this?

Answer 6

Organiser cells differentiate into the axial mesoderm.

The axial mesoderm then involute & intercalate… then undergo convergent extension.

This forms a rod of cells beneath the midline of the induced neural plate.

Question 7

What are the 2 types of axial mesoderm cells?

Answer 7

Prechordal Mesoderm

Notochord.

Question 8

Convergent Extension?

Answer 8

= Part of gastrulation

Question 9

Another Name for Axial Mesoderm?

Answer 9

Chordamesoderm: as this chord of cells is defining feature in chordates.

Question 10

How Does Convergent Extension Relate to Neurulation?

Answer 10

it Drives the transition from neural tube –> neural plate.
(triggers elongation).

Question 11

Invaginate Vs Involute Vs Intercalate:

Answer 11

Invaginate= cells bend inwards.

Involution= epithelial sheet rolls inwards forming an additional underlying layer.

Intercalation= 2 rows of cells move into a thinner longer single row.

Question 12

Polarised nature of the Neural Plate & how molecules can interact with this…?

Answer 12

Apical & Basal sides.

F-actin along the apical (top) edge. When it pulls tight, the cells constrict, creating a curve…

Molecules interact with this F-actin band to trigger the curvature –> leading to neural tube formation.

Question 13

What is Folate & why is it important?

Answer 13

A molecule which interacts with the F-actin band, triggering the formation of the neural tube.

Deficiencies in Folate prevent the neural tube from closing –> leading to birth defects: e.g. spina bifida.

((Folate interacts with receptors on the apical surface –> thus acts as a signal to modify cellular shape))