DV Patterning

Question 1

Organiser cells are induced by signals from what?

Answer 1

Nieuwkoop Centre

Question 2

The organiser expresses which genes?

Answer 2

Chordin, Noggin, Frizbee and Follistatin

ie BMP inhibitors

Question 3

What are the three main precursors that form in the organiser region?

Answer 3

Anterior endoderm
Pre-chordal mesoderm
Notochord
Collectively these are axial mesoderm

Question 4

Which two key events occur once the neural plate has been induced?

Answer 4

Neurulation - formation of the neural tube

Patterning - discrete cells induced in the neural tube

Question 5

What are the two diffusable morphogens involved in patterning the neural tube and where are they from?

Answer 5

BMPs from surface ectoderm

Shh from axial mesoderm

Question 6

Dorsal Patterning by BMPs and BMP signalling?

Answer 6

1) BMPs expressed by surface ectoderm next to the edges of the induced neural plate
2) Neural plate border and roof plate cells induced
3) Secreted BMPs diffuse in to the dorsal neural tube
They induce expression of transcription factors (PAX6, PAX7, PAX3 and Lim1)
These cause cells to acquire ‘dorsal identities’ and form dorsal progenitors

Question 7

Where do BMPs come from?

Answer 7

The roof plate where many different types act as morphogens

Question 8

Which molecule is responsible for ventralisation?

Answer 8

Shh

Question 9

Which structures produce Shh?

Answer 9

Notochord and prechordal mesoderm