Use of osmium etching procedures for studying the ultrastructure of isolated rat islets of Langerhans.

Variants of the osmium etching procedure, described by Tanaka et al. for the demonstration of the structure of organelles by scanning electron microscopy, have been utilized in studies of isolated rat islets of Langerhans. Use of a preliminary glutaraldehyde fixation followed by the osmium etching procedure originally described, allowed effective removal of the cytoplasmic ground substance, as demonstrated by transmission electron microscopy. High resolution scanning electron microscopy of similar preparations permitted studies of the interaction of cytoskeletal elements with individual organelles. In particular, direct interactions of insulin storage granules with cytoskeletal elements were clearly evident.