Observations of the intestinal mucosa using environmental scanning electron microscopy (ESEM); comparison with conventional scanning electron microscopy (CSEM)

In order to evaluate the potential use of environmental scanning electron microscopy (ESEM) in biology, structural changes of the jejunal villi of rats were studied after periods of fasting and refeeding, using a conventional scanning electron microscope (CSEM) and ESEM. While observation using the CSEM, involves chemical fixation, drying and coating, observation of fresh, unprepared materials can be directly realized with the ESEM. Environmental microscopy provides a relatively new technology for imaging hydrated materials without specimen preparation and conductive coating. Direct observation of biological samples in their native state is therefore possible with an ESEM. After fasting, the jejunal mucosa is dramatically reduced in size, splits and holes appearing at the tip of the villi. These changes were observed whatever the type of technique used. Artifacts due to the sample preparation for CSEM observation (drying, coating) can therefore be excluded. However, CSEM and ESEM must be used jointly. While, CSEM must be preferred for surface analysis involving high magnifications, ESEM observation, on the other hand, can prove valuable for determining the living aspect of the samples.