Which fixative is listed as the primary fixative for electron microscopy in this protocol?

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Multiple Choice

Which fixative is listed as the primary fixative for electron microscopy in this protocol?

For electron microscopy, preserving ultrastructure requires strong covalent cross-linking of proteins, which glutaraldehyde provides. It forms stable bonds with amino groups, locking in fine cellular detail and especially membranes, yielding the clear, artifact-free images EM needs. It’s commonly used in buffered solution as the primary fixative, often followed by osmium tetroxide postfixation to boost membrane contrast. Formalin (formaldehyde) is excellent for light microscopy but doesn’t cross-link as effectively for ultrastructural preservation, leading to less reliable membrane and organelle detail. Bouin’s solution and methanol can introduce artifacts or not preserve membranes as well, so they aren’t chosen as the primary fixative for EM.

For electron microscopy, preserving ultrastructure requires strong covalent cross-linking of proteins, which glutaraldehyde provides. It forms stable bonds with amino groups, locking in fine cellular detail and especially membranes, yielding the clear, artifact-free images EM needs. It’s commonly used in buffered solution as the primary fixative, often followed by osmium tetroxide postfixation to boost membrane contrast. Formalin (formaldehyde) is excellent for light microscopy but doesn’t cross-link as effectively for ultrastructural preservation, leading to less reliable membrane and organelle detail. Bouin’s solution and methanol can introduce artifacts or not preserve membranes as well, so they aren’t chosen as the primary fixative for EM.

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