Ultrastructural morphology (chemical fixation)

The samples are fixed with 2.5% glutaraldehyde and 1% paraformaldehyde in 0.1 M buffer. Fixative can be collected at our laboratory prior experiment. After fixation the samples are post-fixed with 1 % Osmium tetraoxide and dehydrated in increasing concentrations of ethanol. After dehydration the samples are embedded in resin (Epon, LR White or Spurr) and polymerized by heat. Ultrathin sections (~ 50nm) are cut with an ultramicrotome, collected on grids and contrasted with uranyl acetate and lead citrate. After air drying the sections are imaged in our TEM at 80kV.

Note: To obtain an optimal morphology it is cruical that the specimen is fixed as fast as possible. If immersion fixation is used, that the size of the sample should be < 1mm³.