Stem Cells. Hope this helps.
Answer:
is one in which blood flows through two capillary beds before being sent back to the heart.
Explanation:
A portal system can be defined as a system of blood vessels having a capillary network at each end, meaning that the blood vessel starts and ends in capillaries, before finding its way back to the heart. The blood draining through the capillary bed flows via the larger vessel to supply the blood to the another structure's capillary bed.
Not including pluto.
Neptune, Uranus, Saturn, Jupiter.
Prokaryotic, it has a flagellum and no nucleus.
