The Use of the Scanning Electron Microscope for the Examination of Sectioned Tissue

Abstract

In previous studies from this laboratory the scanning electron microscope has been used to examine biological materials in the cathodo-luminescense and secondary electron modes. In these studies intact cells or even entire insects have been examined, some in the living state. Epithelial surfaces have been exposed and examined. Prior to the work to be described, no reports of the examination of tissue sections in the scanning electron microscope have been found, although sufaces of solid one millimeter cubes of tissue have been examined.In the present work blocks of solid tissue fixed in buffered aldehyde have been dehydrated in graded alcohols, embedded in paraffin, section at 4μ and examined successfully in the scanning electron microscope. These sections have been over 1 cm square and have been stained for subsequent comparative examination with the light microscope. With the scanning electron microscope in the secondary electron mode, magnifications of X5,000 have been found useful. In addition to the increased resolution as compared to the light microscope, a three dimensional image is obtained. An advantage over the conventional electron microscope is that tissue areas 1,000 times greater may be examined in the large sections without any obscuring grid bars, again with the three dimensional image. With the cathode ray display tube used, magnifications range from X30 to over X20,000