Which fixative is used to preserve lipids and is associated with secondary electron microscopy?

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Multiple Choice

Which fixative is used to preserve lipids and is associated with secondary electron microscopy?

Preserving lipid-rich membranes in electron microscopy requires a fixative that both stabilizes unsaturated lipids and provides heavy-metal contrast. Osmium tetroxide does this by reacting with the double bonds in lipids, fixing and staining them so membranes become electron-dense. This yields strong contrast and is especially useful for secondary electron imaging in SEM, where surface details are enhanced by the heavy-osmium coating. Other fixatives like formalin mainly fix proteins, while potassium dichromate and acetic acid are not lipid-specific and can disrupt membranes.

Preserving lipid-rich membranes in electron microscopy requires a fixative that both stabilizes unsaturated lipids and provides heavy-metal contrast. Osmium tetroxide does this by reacting with the double bonds in lipids, fixing and staining them so membranes become electron-dense. This yields strong contrast and is especially useful for secondary electron imaging in SEM, where surface details are enhanced by the heavy-osmium coating. Other fixatives like formalin mainly fix proteins, while potassium dichromate and acetic acid are not lipid-specific and can disrupt membranes.

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