Effect of dehydroascorbic acid on the islets of Langerhans of the rat pancreas.

Rat pancreatic islets have been studied following successive daily administration of dehydroascrobic acid (DHA) and during the recovery phase following 3 daily injections. One injection of DHA produces degranulation of B cells seen in the light microscope as a loss of aldehyde fuchsin positivity. In the electron microscope the B cells appear to have secretory granules accumulated subjacent to the plasma membranes. Following 2 and 3 daily injections, B cells evidence alterations in the organization of the granular endoplasmic reticulum and mitochondria, and secretory granules are scant but when present are subjacent to the plasma membrane. After 5 to 7 days' recovery few secretory granules remain in B cell cytoplasm, but the cells have prominent granular ER and a Golgi apparatus with numerous prosecretory granules. The primary effect of DHA is an exaggerated secretory response of B cells, which is intensified with subsequent injections. Necrosis of B cells as produced by alloxan is not seen.