The distribution of porcine pancreatic beta-cells at ages 5, 12 and 24 weeks

Islet transplantation is a potential treatment for diabetes mellitus and po rcine pancreata may provide a readily available source of islets. The size, number and distribution of islets within the pancreas may influence the ch oice of age of donor for xenotransplantation. Samples (n = 3 per age group) from the dorsal and ventral pancreas of 5-, 12- and 24-week-old hybrid pig s were fixed in formal saline, processed in paraffin wax and stained with a n avidin/biotin immunohistochemical kit for insulin, glucagon, somatostatin and pancreatic polypeptide. The arrangement of endocrine cells within the pancreata were studied and mean diameter of beta-cell groups were measured (from insulin stained sections) in 1 mm(2) grid areas(n = 10 per section) a nd collated into groups according to size. Percentage volume density of bet a-cells in relation to the whole pancreas was calculated and also the distr ibution of beta-cell groups, according to their size, within the total beta -cell mass. There were differences in the frequency and arrangement of endo crine cells within islets at the different ages studied. beta-Cell groups < 50 mu m in diameter occupied 70 to 80% of the total beta-cell mass at 5 we eks but, as the age of the pig increased, larger cell groups were more abun dant. However, the percentage volume density of beta-cells within the total pancreas did not change as the pancreas matured. This study shows that the endocrine porcine pancreas was maturing and its structure changed between the ages of 5 and 24 weeks. The relevance of these findings may have implic ations on the isolation and function of islets if young pigs are re, be use d as donors for transplantation as a treatment for diabetes mellitus.