Earlier antimonate techniques for electron microscopic localization of sodium were applied
to isolated islets of Langerhans obtained by partial collagenase digestion of mouse and
rabbit pancreas. Incubation of islets in low or high glucose media followed by fixation in
either (a) glutaraldehyde-osmium-antimonate mixtures or (b) osmium-antimonate mixtures
resulted in deposition of precipitation particles in association with organelles directly
involved in insulin secretion: beta granules (saccules) and cell membranes. Precipitation …