What does the colloidal iron stain demonstrate and what controls would you use?

Study for the CAMLPR Histology Practice Test. Study with flashcards and multiple choice questions, each question has hints and explanations. Get ready for your exam!

Colloidal iron staining highlights acidic mucosubstances in tissues by using ferric iron to bind to carboxylated and sulfated mucopolysaccharides and glycoproteins, producing a blue product where these substances are present. This makes it a useful tool for identifying mucins and related glycoconjugates in secretory epithelia and extracellular matrices. It’s not about measuring enzymes, lipids, or just iron deposits, so stains aimed at those components would be different (lipids are shown with lipid stains, enzyme histochemistry reveals enzyme activity, and classic iron deposits are shown with other iron stains). For a proper control, use tissue rich in mucins—such as mucin-containing epithelium of the small intestine (or other mucous-secreting tissue)—to confirm positive staining. In short, the stain reveals carboxylated and sulfated mucopolysaccharides and glycoproteins with ferric iron involvement, and mucin-containing tissue is the appropriate control.