The Marchi Staining Method—Advantages of Dichromate Fixation

Abstract

Extensive experimentation with various combinations for fixation and staining for Marchi positive material, both in Wallerian degeneration and in affected tracts of neurologic mutants, revealed that for mouse central nervous system, and perhaps also cat, best results were obtained by using Muller''s fluid for fixation and Swank-Davenport ingredients or the Poirier-Ayotte-Gauthier modification thereof (Stain Techn., 29, 71-5. 1954) for staining. Fix 4 mm slabs by immersion in 3% potassium bichromate for 1-2 wk and stain 2 wk in 0.5% OsO4, 11 ml; 1% KClO3, 16 ml; formalin (conc.), 3 ml; 10% acetic acid, 3 ml; and distilled water to make 100 ml; or, use the more concentrated original formula. Preparations superior to all other methods were consistently obtained. It seems essential to avoid both perfusion and formalin during fixation to minimize artifact.