Morphofunctional Characteristic of Insulin-Producing Cells of Different Localization in the Pancreas of Intact Rats.

This study is devoted to a comparison of morphofunctional peculiarities and the ratio of apoptosis and proliferation processes in the populations of insulin-producing cells (IPCs) of the pancreas of different localization (pancreatic islets (PIs), single IPCs, and agglomerates thereof) under physiological conditions. A quantitative estimation of the distribution of IPCs of different localization, intensity of immunofluorescent labeling of insulin, and ratio of proliferation and apoptosis processes was carried out on histological preparations of the pancreas. Single IPCs of acinar epithelium have the largest synthetic potential as compared with IPCs of another localization, which is indicated by the maximal values of the intensity of insulin fluorescence and cytoplasm area. Ki-67⁺ IPC are present only in PIs while they are not detected outside the insular part. A majority of TUNEL⁺ IPCs is typical for agglomerates, and TUNEL⁺ IPCs are absent among single IPCs. A direct interconnection between the intensity of fluorescence of islet β-cell insulin and the amount of Ki-67⁺ IPCs in them is detected. The islets with a high intensity of insulin fluorescence also a larger amount of TUNEL⁺ IPCs than do other PIs, which indicates a significant level of their self-renewal. At the same time, a PI with a low content of insulin is characterized by a significant predominance of the process of apoptosis over proliferation. Thus, our data indicate that the structure and functional activity of IPCs depend on the peculiarity of their localization, while their heterogeneity creates the basis for plasticity under the conditions of pathology. [ABSTRACT FROM AUTHOR]