Endocrine cell populations in the pancreas of diabetic WBN/Kob rats.

Numerical changes of insulin-, glucagon- and somatostatin-positive cells in the pancreas of WBN/Kob male rats with spontaneously occurring diabetes were examined. The rats examined were divided into three different age groups: Groups I (12 weeks old) and II (33 weeks old) were clinically prediabetic and group III (60-90 weeks old) was diabetic. Serum glucose value was in the normal range in groups I and II, while it was much higher in group III. B and A cells were markedly decreased in number in groups II and III. In group II, the ratio of B to A cells was normally preserved, though the total endocrine cell number was markedly decreased as compared with that in group I. In group III, the percentage of B cells was decreased significantly. The normal ratio in group II seemed to keep serum glucose within the normal level. In addition to the total endocrine cell reduction, an altered ratio of B and A cells was considered to cause the diabetic condition.