Which pairing correctly matches embedding medium with the typical cutting instrument used?

• A. Glycol methacrylate — rotary microtome
• B. Glycol methacrylate — ultramicrotome
• C. Paraffin — ultramicrotome
• D. Paraffin — cryostat

Answer: (A)

The cutting instrument chosen depends on how hard the embedding medium is and the thickness of the sections you need for light microscopy. Glycol methacrylate is a plastic resin used for LM that yields blocks hard enough to require a rotary microtome, which can produce uniform thin sections suitable for staining and imaging under a light microscope. An ultramicrotome is reserved for ultrathin sections needed for electron microscopy on tougher resins, not typical for glycol methacrylate in LM work. Paraffin blocks are normally cut with a rotary microtome as well, while a cryostat is used for frozen sections, not paraffin-embedded blocks. So the pairing of glycol methacrylate with a rotary microtome is the correct match.