Which microscopy method is used to screen tissue for artificial pigment?

• A. Polarizing microscopy
• B. Brightfield microscopy
• C. Phase-contrast microscopy
• D. Fluorescence microscopy

Answer: (A)

Polarizing microscopy uses polarized light to reveal birefringent substances in tissue. Many artificial pigments are crystalline and interact with polarized light by changing its plane of vibration, producing bright interference colors that stand out against the dark background of non-birefringent tissue. This makes it particularly effective for screening tissue for foreign or artificial pigments such as talc or other crystalline fillers, which can be missed with standard brightfield methods. In brightfield, pigments are seen mainly by color from stains and may be masked if they’re colorless or small; phase-contrast enhances contrast in unstained specimens but isn’t specific for pigment, and fluorescence depends on the pigment's ability to fluoresce, which isn’t reliable for routine screening.