Progress in the study of Biological specimens using ESEM

Abstract

In all areas of electron and optical microscopy, the challenges posed by biological specimens have long provided the stimulus for new and inventive means for their handling, processing and imaging. This paper discusses various recently developed approaches to the study of uncoated hydrated biological specimens using scanning electron microscopy (SEM), environmental SEM (ESEM) and scanning transmission electron microscopy in ESEM (ESEM-STEM). Specifically, a method is described for observing unfixed, even live organic specimens at higher temperatures and pressures than is normally associated with ESEM. It is shown that specimens can be successfully maintained in a hydrated state and imaged under relatively ambient conditions, e.g. room temperature and water vapour pressures up to 20 torr (~2.7 kPa), suggesting that it should be possible to provide organic specimens with a near-physiological environment in this type of instrument.