A simple stain for myelin in frozen sections: a modification of Mahon's method.

A simple and rapid method for demonstrating myelinated nerve fibers in frozen sections of the central and peripheral nervous system is described. Material fixed by perfusion with mixed aldehydes gives the best results but the method also works on specimens fixed by immersion in formaldehyde. Frozen sections varying in thickness from 15-50 micron are mounted on slides subbed with chrome alum-gelatin. After hydration (60-120 min), sections are mordanted (20-40 min) in 2.5% iron alum and rinsed briefly in three changes of distilled H2O (total 2 min). Staining is for 60-180 min in 20 cc freshly made 10% alcoholic hematoxylin diluted with 165 cc distilled H2O to which 15 cc saturated Li2CO3 is added. The sections are washed in distilled H2O (5-15 min) and dehydrated in graded alcohols without differentiation in mordant, and covered. Myelin stains a dark blue-purple against a light grey background. Fiber tracts, as well as individual myelinated fibers, are clearly demonstrated.