A Method for Direct Observation of Botanical Tissues and Intracellular Contents by SEM

Abstract

When biological (non-conducting) specimens are examined in the scanning electron microscope (SEM), local accumulations of electrons (charging) on the surface of the tissue obscure information and prevent accurate imaging. In order to prevent this surface accumulation, low accelerating voltages (1 Kv and less) have been employed at the expense of resolution. Ideally tissue should be examined fresh, uncoated. Fresh tissues rarely conduct well enough to be examined however, and for this reason some investigators bathe specimens in solutions such as gold chloride and uranyl nitrate which act as a source of ionic material within the tissue. Although this method increases conductivity, it does not make the tissue any less vulnerable to the effects of the vacuum or electron beam.