Preservation of Soluble Proteins for Histological Staining in Paraffin Sections

Human serum at full strength and in dilutions with physiological saline (0.85%) ranging from 1:1 to 1:72 was allowed to permeate rectangular masses of fibrin foam in small pieces (maximum diameters 0.2 × 0.4 × 1.0 cm), and then placed in 10% neutral formalin, Zenker's solution and Bouin's solution. After fixation for 4-12 hr, the fibrin foam and occluded serum proteins were imbedded, sections cut and stained with eosin bluish (CI. 771), 0.25% alcoholic solution, and by the McManus periodic acid-Schiff technique, using basic fuchsin (CI. 677). Undiluted serum (6.4 gin 100 ml) was not stainable after fixation in 10% formalin. With Zenker's solution stainable serum proteins are recognizable at 0.22 gm/100 ml and with Bouin's solution at 0.08 gm/100 ml. Dried aliquots (0.2 ml) of the same dilutions, spread over an area of 1.0 cm², fixed and stained similarly, gave almost identical results.