Glutaraldehyde is frequently used to fix specimens for electron microscopy.

• A. True
• B. False
• C. Only for light microscopy
• D. Never used

Answer: (A)

Glutaraldehyde is chosen for electron microscopy because it forms strong covalent crosslinks between proteins, creating a rigid and well-preserved ultrastructure. This excellent stabilization of membranes and fine cellular details is exactly what high-resolution EM requires, allowing you to see organelles and networks with great clarity after embedding and sectioning. In practice, it’s used as a primary fixative in buffered solution (often around 2–3%) and is typically followed by postfixation with osmium tetroxide to fix lipids and enhance membrane contrast. For light microscopy, glutaraldehyde isn’t ideal due to slower penetration and potential issues with staining and antigenicity, so formaldehyde-based fixatives are more common there. That’s why the statement is true: glutaraldehyde is frequently used to fix specimens for electron microscopy.