The Application of the Prussian Blue Stain to Previously Stained Films of Blood and Bone Marrow

A simple method for staining non-hemoglobin iron in erythrocytes, normoblasts, macrophages, and other cells containing particulate iron in new or old films of cellular fluids or imprints of tissues and organs is presented. This method consists in using the prussian blue reagent as a type of counterstain; no separate decolorization is necessary. The preparations obtained resemble the original preparations except that iron stands out as a vivid blue-green material.

The method is particularly useful in studying conditions accompanied by varying degrees of iron excess or hemosiderosis of the marrow.

The stainable iron is all virtually the same color. The diffuse blue-green color of the cytoplasm of macrophages might be attributed to the more soluble form of iron, ferritin.

Stainable iron is visible in normoblasts and erythrocytes as well as in macrophages in sections subjected to the prussian blue reaction.

A prussian blue method using formalin fixation on fresh films of marrow⁷ has also been shown to be useful in the demonstration of particulate iron in previously stained films of marrow and blood. The formalin fixation appears to bring about a higher percentage of siderocytes.