Vertebrate limb development

Question 1

What are Tbx5 and Tbx4 required for?

Answer 1

Tbx5-> forelimb

Tbx4-> hindlimb

Question 2

What does the Hox code do?

Answer 2

The hox code controls the expression of the Tbx5 and Tbx4 (by inducing RA)

Question 3

What controls the production of FGF and what does it do?

Answer 3

The Tbx genes control production of FGFs

FGFs initiate limb development

Question 4

What happens when FGF is applied to the posterior interlimb region?

Answer 4

Leg buds develop

Question 5

What gene is required for Tbx4 expression?

Answer 5

Pitx1

Question 6

What does FGF10 expression induce?

Answer 6

FGF8 expression in the overlying ectoderm that will form the AER

Question 7

The AER is necessary for the ….

Answer 7

Progress zone

Question 8

What are the 2 models for proximal-distal patterning of the limb?

Answer 8

1. Progress zone model

2. Two signal model

Question 9

How does the ZPA control antero-posterior patterning?

Answer 9

It is a source of the Shh morphogen- digits specified at different concentrations of Shh

Question 10

Which gene codes for the stylopod?

Answer 10

Meis

Question 11

Which gene codes for the Zeugopod?

Answer 11

Hox11

Question 12

Which gene codes for the autopod?

Answer 12

Hox13

Question 13

What is the stylopod?

Answer 13

The humerus

Question 14

What is the zeugopod?

Answer 14

The ulna and radius

Question 15

What is the autopod?

Answer 15

The carpals and the digits