Dichromate-Chlorate Perfusion Prior to Staining Degeneration in Brain and Spinal Cord

A method of fixation compatible with both the Nauta-Gygax and Swank-Davenport procedures for degenerating nerve fibers, which shortens the time required by the former procedure, is as follows: The central nervous system is perfused with a 0.9% aqueous solution of NaCl followed by an aqueous solution containing 5% K₂Cr₂O₇ and 2.5% KClO₃. The central nervous system is then hardened in 10% formalin for 1-3 days. Tissue for Marchi-type staining can be taken at this stage. For silver staining, the processing is continued by immersion overnight in 10% formalin in 20% alcohol, and frozen sections cut the next day. Sections, up to 50μ in thickness, are collected in 10% formalin and impregnated by the Nauta-Gygax technique. Best results are obtained by impregnating within 24-48 hr after sectioning.