Carbowax processing (Polyethylene glycol) has which disadvantage?

• A. It is water soluble, so sections cannot be floated on a water bath
• B. It dissolves lipids
• C. It requires heat
• D. It causes extensive shrinkage

Answer: (A)

Carbowax (polyethylene glycol) embedding relies on a medium that is soluble in water. Because PEG is water soluble, tissue sections embedded in it cannot be floated on a water bath to adjust thickness or to flatten properly, as would be done with paraffin sections. Placing PEG-embedded sections on water would cause the medium to dissolve, tearing or detaching the tissue from the slide. This inherent property is the main drawback of Carbowax processing, limiting its compatibility with standard flotation techniques. The other statements don’t reflect this major limitation: PEG doesn’t inherently dissolve lipids in the way the option suggests, and while heating is involved in the process, that isn’t the defining disadvantage in the same way the water solubility is.