Question

Renal portal system is absent in:

• A. Amphibians
• B. Reptiles
• C. Amphibians and reptiles
• D. Mammals

Answer 1

Answer: (D)

• The renal portal system is derived from the posterior cardinal veins found in fishes, amphibians, and reptiles.
• It is absent in hagfish, lampreys, and mammals.
• Blood from the posterior part of the body flows into the renal portal veins, which pass into the caudal vena cava.

Thus, the correct answer is option D.