A new preparatory technique for scanning electron microscopy of soft biological tissues using partial resin embedding: Applications on the human retina and the guinea pig renal glomeruli

Abstract

Preparation of soft biological tissue for scanning electron microscopy in the reflective and emissive modes is most often made with freeze drying. In a rather unpredictable way, however, the preservation sometimes proves unacceptable, no doubt because of the physico-chemical properties and anatomical characteristics of the tissue. Attempts made by the author to visualize interior structures of certain types of tissue, among them the human retina prepared by freeze drying from water or amyl acetate were not successful, nor were other techniques of dehydration. The common characteristics of the retina, established in the past with light microscopic techniques and with thin section transmission electron microscopy, could not be retrieved in the final scanning picture. Especially deleterious effects were demonstrated in the spatial relationship between the tissue components, and often the cells were shrunken and deranged to the point of not being recognizable. The shrinkage also produced large empty spaces between the cells. Another method of preparation was therefore devised the details of which are described in the present paper together with examples of applications.