A good control tissue for this staining protocol is which?

• A. Small intestine
• B. Brain
• C. Skeletal muscle
• D. Skin

Answer: (A)

When choosing a control tissue, pick one that naturally contains the substance or feature your stain is designed to reveal, so you can verify the staining reagents and protocol are working.

For mucin-staining protocols, the small intestine is ideal because goblet cells there produce abundant mucin, giving a strong, consistent positive signal that clearly demonstrates the stain is performing correctly. In contrast, brain and skeletal muscle have little to no mucin in the typical context of routine staining, and skin contains far less goblet cell mucin, making them poor positives for confirming mucin staining.