Morphological characterization of membrane systems in A- and B-cells of the Chinese hamster

The nuclear and plasma membranes of islet cells from non-glycosuric and diabetic Chinese hamsters were examined by freeze-etching. The B-cells of diabetic animals presented a slight increase in the number of nuclear pores and marked alterations in the number, size and distribution of membrane-associated particles in the plasma membrane. In A-cells, identified by the presence of characteristic bundles of coarse filaments in the perinuclear region, a definite increase in the number of nuclear pores was found in the most severely diabetic animals. These preliminary findings point to alterations in the membrane systems as possible determinants for the abnormalities of islet function in diabetes mellitus.