Silver Impregnation of Degenerating Axons in the Central Nervous System: A Modified Technic

TLDR: Frozen sections of formalin-fixed brains containing surgical lesions, were treated with 15% ethanol for 0.5 hr, and subsequently treated with 0.05% potassium permanganate for 4–10 min, and covered in neutral synthetic resin.

Abstract: Frozen sections of formalin-fixed brains containing surgical lesions, were treated with 15% ethanol for 0.5 hr., soaked in 0.5% phosphomolybdic acid for 0.25–1.0 hr., and subsequently treated with 0.05% potassium permanganate for 4–10 min. (The duration of the latter treatment is critical and individually variable). Subsequent procedure is as follows: decolorize in a mixture of equal parts of 1% hydroquinone and 1% oxalic acid; wash thoroughly and soak sections in 1.5% silver nitrate for 20–30 min.; ammoniacal silver nitrate (silver nitrate 0.9 g., distilled water 20 ml., pure ethanol 10 ml., strong ammonia 1.8 ml., 2.5% sodium hydroxide 1.5 ml.) 0.5–1.0 min.; reduce in acidified formalin (distilled water 400 ml., pure ethanol 45 ml., 1% citric acid 13.5 ml., 10% formalin 13.5 ml.) 1 min.; wash, and pass section through 1% sodium thiosulfate (0.5–1.0 min.); wash thoroughly and pass sections through graded alcohols and xylene (3 changes); cover in neutral synthetic resin.