Transmission Electron Microscopy of Cell Profiles
Transmission Electron Microscopy (TEM) plays a major role in biological sciences and in the assessment of biological safety, particularly in virology. The technique allows visualisation of virus particles, both in biological fluids and in vitro. It allows direct visualisation of particle size and morphology, intra- and extra-cellularly. TEM is recommended in several guidelines, specifying which materials require testing, including cell lines, culture supernatants and fermenter bulk harvests. These include the Federal Drug Administration (FDA), European Medicines Agency/International Committee for Harmonisation (EMEA/ICH) and European Pharmacopeia (Ph.Eur.). TEM is also significant in diagnostic virology where it remains a reliable technique to identify viruses in biological samples. TEM allows the direct visualisation of cells and micro-organisms at the ultrastructural level. It can reveal the size, structure and location (intra- or extra-cellular) of viruses or virus-like particles, and fungal, mycoplasma or bacterial contamination associated with the cells examined. Vitrology offers protocols for the observation of viruses, virus-like particles, adventitious and other extraneous agents by TEM of at least 200 cell profiles. The studies record the percentage of cells with which they are associated.