Which of the following statements is true about basement membranes during demonstration?

• A. They should be cut at 2 nm
• B. They should be cut at 20 micrometers
• C. Thickness is not critical
• D. They do not require sectioning

Answer: (A)

Basement membranes are extremely thin extracellular structures, so the thickness of the section you cut directly affects whether you can visualize them clearly under the chosen microscope. For demonstrations that use electron microscopy, you need ultrathin sections on the order of tens of nanometers—commonly about 60–90 nm—so the beam can pass through and produce a usable image. Cutting sections as thin as 2 nanometers is not realistic with standard microtomy and would not yield a stable, interpretable slice; it’s far thinner than typical ultrathin sections and not how these demonstrations are normally prepared. Conversely, cutting a section as thick as 20 micrometers would be far too thick for either light or electron microscopy, leading to poor resolution and obscured details. Thickness is indeed critical: too thick or too thin compromises staining, penetration, and resolution, and you wouldn’t skip sectioning because the basement membrane sits within tissue and requires a proper cut to be seen. In practice, use paraffin sections around 4–6 micrometers for light microscopy, or ultrathin sections around tens of nanometers for electron microscopy when demonstrating basement membranes.