Quarterly Journal of Microscopical Science, Vol s3-105, 99-105, Copyright © 1964 by Company of Biologists

Further Uses and Methods of Processing of Fresh Frozen Sections of Peripheral Nerve

¹ Department of Anatomy, Guy's Hospital Medical School, London
² Department of Anatomy, Guy's Hospital Medical School, London. Prof. C. P. Wendell-Smith's address is: School of Anatomy, University of New South Wales, Australia

Advantageous modifications of a fresh frozen sectioning technique for peripheral nerve (Williams, 1959) include reduction in size of the block of supporting tissue, the use of human hair as a ligature, the multiple embedding of specimens and the use of liver sandwiches for irregular specimens. Observation with oblique incident illumination indicates that fresh sectioned fibres remain approximately cylindrical. Fresh sections treated for 5 min with common fixatives such as 10% formal saline, Bouin's fluid, and Flemming's fluid show widespread changes in the outline, texture, and dimensions of the myelin sheaths. A modified Flemming fixation/haematoxylin staining method may be used with fresh sections; this gives reasonable preservation of the external sheath boundary but is unsuitable for measurements of internal diameter. Luft's buffered potassium permanganate solution provides an easily standardized, effective method of producing permanent preparations for quantitative studies. Holmes's silver impregnation technique may be adapted for use with fresh frozen sections. Interferometric estimations may be made upon axoplasm using 5 µ fresh frozen sections in saline. Care must be taken to determine the axoplasmic thickness present. Adequate sampling of an extended section, when using shearing system objectives, may be accomplished by serial stripping of the section under the dissecting microscope.