Hexamethyldisilazane: A modified procedure

Abstract

Scanning electron microscopy is a powerful tool in the study of cell contact in vitro, and has shown, specifically, that fibroblasts under conditions of growth restriction increase cell contact by filopodia. Accurate quantitation of surface features like filopodia, however, depends particularly upon artifact-free drying procedures. Critical point drying (CPD) of fibroblast monolayers all too often causes cell flattening, shrinkage, loss of surface detail and cracking (Fig. 1). Newer methods utilizing hexamethyldisilazane (HMDS) and uranyl acetate (UA) preserve fibroblast contour and surface architecture better than CPD, but solvent choice in the preparation of UA is of critical importance. UA in 70% ethanol results in the formation of precipitate (Fig. 2) whether the specimens are in the cold (4°C) or at room temperature, overnight or for periods less than 1 hour regardless of filtering. It occurs when incubation is carried out in the dark and when it is followed by copious rinses in 70% ethanol.