​In birds and mammals, the 3rd, 4th, and 6th aortic arches persist in adult animals with some structural modifications. Which of the following modified organizations is correct?

Correct option is B

​Explanation:

In vertebrate embryology, the aortic arches undergo significant remodeling, forming major arteries in adult birds and mammals. The 3rd, 4th, and 6th aortic arches persist in a modified form:

• 3rd Aortic Arch: Forms the common carotid arteries and the proximal internal carotid arteries.
• 4th Aortic Arch:
• In birds: The right 4th arch forms the right systemic arch (not the left).
• In mammals: The left 4th arch forms the systemic aortic arch.
• 6th Aortic Arch:
• In both birds and mammals, it contributes to the pulmonary circulation.
• In mammals, it forms the pulmonary arteries and the ductus arteriosus (which later becomes the ligamentum arteriosum after birth).

Information Booster

1. The 3rd aortic arch contributes to the carotid artery formation.
2. The 4th aortic arch develops into the systemic aorta in mammals (left) and birds (right).
3. The 6th aortic arch contributes to the pulmonary arteries and ductus arteriosus.
4. The first and second aortic arches disappear in early embryonic development.
5. The ductus arteriosus allows fetal blood to bypass the lungs before birth.
6. In adult mammals, the ligamentum arteriosum is the remnant of the ductus arteriosus.