Scanning electron microscopy of surface changes on dispersed pancreatic beta-cells following stimulation of insulin release.

The surface structure of isolated, viable beta-cells was studied by scanning electron microscopy. Suspensions of islet cells wuse. Cells incubated with and without D-glucose were fixed while in suspension, filtered onto Nucleopore filters and prepared for scanning electron microscopy by the critical point drying procedure. After incubation in glucose-free medium the cells were spherical with surface blebs and occasional small pits. Cells stimulated with 20 mM D-glucose and 0.1 mM 3-isobutyl-1-methyl-xanthine exhibited a two-fold increase in the number of blebs and in insulin release. The increased number of blebs was still seen in a Ca++ deficient medium, and may, therefore, not necessarily reflect an insulin extrusion phenomenon. It is concluded that D-glucose induces alternations of the surface morphology in isolated beta-cells in suspension.