The blood vessel that branches from the subclavian artery to supply the anterior wall of the chest is the
A) internal thoracic.
B) azygos artery.
C) mediastinal artery.
D) thoracic aorta.
E) vertebral artery.
Question 2
The region known as the primitive streak is the site of
A) migration of mesodermal cells to form the endoderm.
B) endoderm formation.
C) ectoderm formation.
D) migration of ectodermal cells to form the mesoderm.
E) amnion formation.