This is useful for demonstrating both hydrophobic and hydrophilic lipids:

• A. OTAN
• B. Oil Red O
• C. Nile Blue Sulfate
• D. Sudan Black B

Answer: (A)

A staining approach that can reveal both hydrophobic and hydrophilic lipids is looking for a way to visualize all lipid components in a tissue, not just one subset. Lipids come in polar and nonpolar forms: nonpolar fats like triglycerides and cholesterol esters, and polar lipids such as phospholipids and glycolipids with phosphate or sugar groups. Demonstrating both types in the same section gives a complete picture of lipid distribution and storage.

OTAN is described as the method that best accomplishes this because its staining action can interact with a broad range of lipid classes, making both neutral (hydrophobic) and polar (hydrophilic) lipid components visible in the same specimen. This provides a more comprehensive view of lipid content than stains that primarily target one lipid class.

By contrast, other lipid stains tend to be more selective: some emphasize neutral lipids, others differentiate lipid classes but don’t show every lipid type with the same clarity, or require additional steps to separate hydrophobic from hydrophilic lipids. OTAN’s broad applicability makes it especially useful when the goal is to demonstrate the presence and distribution of all lipid types within a sample.