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Dissection technique for cochleas prepared for scanning electron microscopy.

Rydmarker-S; Dunn-DE; Nilsson-P; Lindqvist-C
Scanning Electron Microsc 1986 Jan; 4:1459-1467
A dissection method (anchor technique) was described for overcoming curling of the basilar membrane during critical point drying in the preparation of cochlear specimens for the scanning electron microscope (SEM). The method was tested using guinea-pigs. All the structures above the reticular lamina were removed, but the basilar membrane was left attached to the spiral ligament and the lateral bone to which the spiral ligament was anchored. A 0.5 millimeter diamond burr was used to open the bone lateral to the scala vestibuli of each turn of the cochlea. Individual turns were dissected and mounted on the same examination stub for SEM evaluation. Artifacts were detected in approximately 20 percent of the cochleas, but morphologic evaluation was still possible in 95 percent. The procedure eliminated curling which occurred with the revised tannin/osmium (Murakami) and modified thiocarbohydrazide (OTO) techniques for preparing cochlear tissues, to the point where curling was not a problem in photomicroscopy or in evaluation of morphology. Both large and small cracks caused by critical point drying occurred more often with the anchor technique than when both the bony ring and the spiral ligament were removed. Thus, removing the bone and spiral ligament caused more curling and less cracking, whereas the anchor technique caused more cracks and less curling. Because of the drilling, bone dust was more common with the anchor technique, but it did not cause any major evaluation problems. The authors conclude that the technique requires additional dissection time, but that once mastered, it gives results that justify the effort, making possible a complete evaluation of the structures of the reticular lamina from the lateral or modular side. The authors recommend the technique when quantification of cochlear surface morphology is needed.
NIOSH-Author; Ears; Microscopic-analysis; Laboratory-techniques; Auditory-system; Microscopy; Sample-preparation; Laboratory-animals; Histomorphology;
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Scanning Electron Microscopy
Page last reviewed: September 2, 2020
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