The specialized water channels that allow water to cross cell membranes efficiently are called:

1. Water itself can slip through membranes somewhat, but movement is greatly sped up by dedicated channels. 2. These channels aquaporins. 3. Ion channels and glucose transporters move solutes, not bulk water, so they are ruled out. 4. Therefore aquaporins is correct. _Source: OpenStax Anatomy and Physiology (CC BY 4.0), Ch 26 "Fluid, Electrolyte, and Acid-Base Balance", p.1254 §Solute Movement between Compartments_