Protargol impregnation of plastic-embedded semi-thin sections: A simple method to select degenerative areas for electron microscopy

Abstract

0.5μ, plastic-embedded sections, obtained from aldehyde-osmium fixed rat and cat spinal cord, were impregnated in a 0.5% Protargol solution for 24 hours at 56°C. Reduction was performed in a sodium sulphite-(5%) hydroquinone (1%) developer. Terminals undergoing Wallerian degeneration stand out as easily discernible black dots; corresponding osmiophilic degenerative patterns are demonstrated in consecutive thin electron microscopic sections. This simple technique enables successful trimming of blocks to obtain areas with the highest frequency of terminal degeneration.