A new development involves a network of plastic tubes being printed within an organ. After the whole organ is printed, these plastic tubes are dissolved, leaving a network of empty tunnels. Why does the organ need to have the empty tunnels within it?

These are needed to mimic the blood vessels which these organs will use for the supply or drainage of fluids e.g blood.

In addition the empty tunnels serve as the routes for nutrients and oxygen supply  for the organ.

In summary the tunnels provided  a vascular structure to support the organ

Explanation:

answer; the above answer to the above statement is (true)

true                                                                                                       true true true true true true