HISTOMORPHOLOGICAL PECULIARITIES OF THE PANCREATIC PARENCHYMA IN RATS WITH ALLOXAN-INDUCED DIABETES OF DIFFERENT DURATION

The study of pathohistological and morphofunctional changes in the endocrine pancreas is an integral part of experimental diabetology, which allows obtaining a signifi cant amount of information on various aspects of the etiology and pathogenesis of diabetes and its complications using experimental animal models. Aim of the study was to conduct a comprehensive evaluation of histostructure peculiarities of the pancreas and the reparativepotential of the aff ected pancreatic islets of Langerhans in rats with alloxan- induced experimental diabetes mellitus (EDM) of diff erent duration.Materials and methods. The experiments were performed on 63 white non-linear adult male rats, experimental diabetes mellitus (EDМ) was induced in 53 of them (10 intact rats served as control group). At 10, 20, 25, 30, 40 and 45 days after the administration of the diabetogenic substance, the experimental animals were withdrawn from the experiment, the pancreas was removed and serial sections were made, stained with hematoxylin and eosin according to the standard technique, as well as with aldehyde fuchsin – for the identifi cation of β-cells of the islets of Langerhans. To quantify the endocrine part of the pancreas, the average diameter of the islets of Langerhans (μm), the average number of cells in the islets of Langerhans in the profi le of the histological section, as well as the specifi c volume of the islets of Langerhans in the pancreatic tissue (%) were studied in serial histological sections.Results. The course of alloxan- induced EDM was accompanied by signifi cant destructive- degenerative changes in the pancreatic islets during all observation periods. On the 11th day after alloxan administration, most of the cells of the islets of Langerhans were in a state of necrosis with signs of karyopyknosis and karyorrhexis. As a result of alterative processes, the number and size of islets of Langerhans, their specifi c volume in the pancreatic tissue, and the average number of cells in them were greatly reduced. No specific staining of β-cells with aldehyde fuchsin was detected. Moderate swelling of the pancreatic interstitium, focal dystrophic processes in the epitheliocytes of the exocrine pancreas, sometimes with pronounced microcystic formations, were found on the 11th day of the experiment. On the 21st and 26th day after alloxan administration, the specifi c volume, the size of the pancreatic islets of Langerhans and their cellularity parameters continued to decrease r