Which stain is most likely to show colloidal iron deposition in tissue sections?

• A. Colloidal Iron
• B. Prussian Blue
• C. Alcian Blue
• D. Masson Trichrome

Answer: (A)

Understanding what each stain highlights helps explain why this option is the best. Colloidal iron staining is a method specifically designed to bind iron-containing colloids to acidic mucopolysaccharides and glycoproteins in tissue. When tissue sections are treated with the colloidal iron reagent, iron deposits appear as blue granules where these substances are present, making colloidal iron deposition directly visible.

Prussian blue, by contrast, detects ferric iron (Fe3+), such as hemosiderin or ferritin, through a blue reaction product. It is not used to visualize colloidal iron deposition associated with mucopolysaccharides.

Alcian Blue stains acidic mucopolysaccharides and glycosaminoglycans, but it does so by dye affinity, not by depositing iron colloids.

Masson Trichrome differentiates tissue components like collagen, muscle, and cytoplasm using a series of dyes, without involving iron deposition.

So the stain whose purpose is to demonstrate colloidal iron deposition in tissue sections is the Colloidal Iron stain.