Sample interview questions: Discuss your knowledge of different types of stains for electron microscopy.
Sample answer:
-
Heavy metal stains:
- Osmium tetroxide (OsO4):
- Commonly used as a primary fixative for electron microscopy.
- Reacts with unsaturated lipids, preserving membrane structures.
- Also used as a contrasting agent, enhancing the visualization of cellular components.
- Uranyl acetate (UA):
- A commonly used post-fixative and contrasting agent.
- Binds to phosphate groups in nucleic acids and proteins, providing electron density.
- Enhances the contrast of cellular structures, particularly nucleoproteins.
- Lead citrate (Pb Cit):
- A post-staining agent used to enhance the contrast of biological specimens.
- Binds to phosphate groups in nucleic acids and proteins, increasing electron density.
- Often used in conjunction with uranyl acetate for double staining.
- Osmium tetroxide (OsO4):
-
Non-heavy metal stains:
- Potassium permanganate (KMnO4):
- A fixative and contrasting agent used for electron microscopy.
- Reacts with double bonds in lipids, preserving cellular structures.
- Provides good contrast for lipid-rich tissues and membranes.
- Phosphotungstic acid (PTA):
- A negative staining agent used for electron microscopy.
- Binds to positively charged molecules, such as proteins and nucleic acids.
- Creates a dark background against which unstained cell… Read full answer
- Potassium permanganate (KMnO4):