Studies in the diabetic mutant mouse: I. Light microscopy and radioautography of pancreatic islets

Abstract

Light microscopic and radioautographic studies were performed in normal (C 57 BL/KsJ) and in diabetic mutant (C 57 BL/Ks-db/db) mice following thymidine-3H administration. The pancreatic islets of normal mice were small, beta cells well granulated and a rare islet cell incorporated thymidine-3H. In prehyperglycemic mutants (blood glucose < 120 mg/100 ml) beta cells were also well granulated but incorporated thymidine-3H with greater frequency than observed in normal mice. With the onset of early hyperglycemia (blood glucose 130-200 mgm/100ml) and hyperinsulinemia, the islets were normal in size, however beta cells were partially degranulated and numerous islet cells were labeled with thymidine-3H. With established hyperglycemia (blood glucose < 200 mg/100 ml) serum IRI was greatly increased, beta cell degranulation pronounced, labeled islet cells numerous, and islet enlargement noteworthy. The terminal phase of the syndrome was characterized by a decrease in the number of beta cells and a unique proliferation of small ductal structures. Labeled ductal cells were numerous, labeled endocrine islet cells infrequent and the animals succumbed in a state of relative insulin insufficiency. © 1970 Springer-Verlag.