Chapter 10 Questions

Question 1

Which of the following molecules plays an important role in the determination of the dorsoventral axis of the developing limb?
A. Msx-1
B. Wnt-7a
C. Hoxd-13
D. Pax-1
E. FGF-8

Answer 1

B. Wnt-7a

Question 2

What molecule is associated with myogenic cells migrating into the limb bud from the somites?
A. Shh
B. BMP-7
C. FGF-4
D. Pax-3
E. En-1

Answer 2

D. Pax-3

Question 3

What is the principal function of the AER?
A. Stimulating outgrowth of the limb bud
B. Setting up the anteroposterior axis of the limb bud
C. Determining the specific characteristics of the ectodermal appendages of the limb
D. Determining the pattern of neural ingrowth into the limb
E. Attracting the subcutaneous plexus of capillaries in the limb bud

Answer 3

A. Stimulating outgrowth of the limb bud

Question 4

In the developing limb the sonic hedgehog (shh) gene product is produced in the:
A. Progress zone
B. Region of interdigital cell death
C. ZPA
D. AER
E. Common muscle mass

Answer 4

C. ZPA

Question 5

The formation of clubfoot (talipes equinovarus) is associated with:
A. A misplaced ZPA
B. Defective cellular migration from somites
C. Thalidomide
D. Oligohydramnios
E. A neural crest defect

Answer 5

D. Oligohydramnios

Question 6

If the somites close to a limb-forming region are experimentally removed, the limbs form without muscles. Why?

Answer 6

Muscle-forming cells arise from the somites

Question 7

A child is born with wedded fingers (syndactyly). What is the reason for this anomaly?

Answer 7

The cause is likely the absence of programmed cell death in the interdigital mesoderm