The onset and progression of pancreatic insulitis in the overt, spontaneously diabetic, young adult BB rat studied by pancreatic biopsy.
A specially developed clamping procedure permitted the easy, complication-free removal of splenic pancreas from rats. Using this biopsy procedure pancreatic tissue was removed from 50- to 90-day-old BB rats to study in a retrospective experimental design the time at which insulitis appears in BB rats, which develop acute, overt diabetes before the age of 120 days. Islets in biopsies taken 18-53 days before the onset of diabetes showed normal structure and were free from any mononuclear infiltrations. Biopsies removed between 2 and 9 days before onset of diabetes in contrast showed widespread insulitis. In five rats in which the biopsy preceded the manifestation of diabetes by 11-16 days, only a small number of pancreatic islets showed small focal mononuclear cell infiltrations. Most of the islets in these five rats had a normal histologic appearance. Thus the lesions within the islets develop rapidly starting about 2-3 wk before overt diabetes. As revealed by autoradiography, pancreatic beta-cells still surviving at the time of onset of diabetes show a modest increase in replicative activity. Replicative activity of mononuclear inflammatory cells also was observed, suggesting that their accumulation within the islet tissue may result in part from local replication.
D000818:Animals; D001706:Biopsy; D003921:Diabetes Mellitus, Experimental / Q000473:pathology*; D003922:Diabetes Mellitus, Type 1 / Q000209:etiology / Q000473:pathology*; D005260:Female; D007515:Islets of Langerhans / Q000473:pathology*; D008297:Male; D010179:Pancreas / Q000473:pathology*; D051381:Rats; D011919:Rats, Inbred Strains