If iron alum is skipped in Gordon and Sweet's reticulin stain, reticulin fibres appear as which?

• A. Not demonstrated
• B. Blue
• C. Red
• D. Yellow

Answer: (A)

Reticulin visualization with Gordon-Sweet relies on a mordant to anchor silver onto the reticular fibers. Iron alum acts as that mordant, helping silver deposition so the reticulin network becomes visible as dark structures. If iron alum is skipped, silver cannot bind to the reticulin, so the fibers are not demonstrated and appear essentially absent. Other colors described in different stains or with different steps don’t apply here; the key point is that without the mordant, the reticulin network won’t be visualized.