Which fixative is not suitable for electron microscopy?

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Multiple Choice

Which fixative is not suitable for electron microscopy?

Electron microscopy relies on fixatives that lock in ultrastructure, especially membranes, without removing lipids or leaving residues that interfere with heavy-metal staining and resin embedding. Bouin's fixative contains picric acid, which fixes proteins but tends to extract lipids and can leave interfering residues. That lipid loss and residue disrupt membrane preservation and the subsequent osmium tetroxide steps that provide the necessary contrast in EM. Because of this, Bouin's is not suitable for electron microscopy, whereas EM protocols favor fixatives like glutaraldehyde (often followed by osmium tetroxide) that preserve membranes and lipids more reliably.

Electron microscopy relies on fixatives that lock in ultrastructure, especially membranes, without removing lipids or leaving residues that interfere with heavy-metal staining and resin embedding. Bouin's fixative contains picric acid, which fixes proteins but tends to extract lipids and can leave interfering residues. That lipid loss and residue disrupt membrane preservation and the subsequent osmium tetroxide steps that provide the necessary contrast in EM. Because of this, Bouin's is not suitable for electron microscopy, whereas EM protocols favor fixatives like glutaraldehyde (often followed by osmium tetroxide) that preserve membranes and lipids more reliably.

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