An immunofluorescent study of insulin-, glucagon-, pancreatic polypeptide- and somatostatin-containing cells in the early ovine fetal pancreas.

Using antisera to insulin, glucagon, pancreatic polypeptide (PP) and somatostatin, the localization and cellular distribution of the four hormones were investigated in the sheep fetal pancreas of day 40-45 gestation by immunofluorescence. All four hormones were immunolocalized at this early gestational period. The endocrine cell types had a characteristic distribution and were present in different numbers. Insulin and glucagon immunoreactive cells were seen in larger numbers compared to fetal PP and somatostatin cells and were located either in the developing islets or as single scattered cells in the epithelium of the embryonic ductules. These cells became more confined to the developing islets at later stages of gestation. In the pancreas of day 40-45 fetuses PP cells were less numerous than glucagon and insulin cells while somatostatin cells were seen rarely. However, PP and somatostatin cells became more numerous at later stages of gestation. Our studies demonstrate the presence of insulin, glucagon, PP and somatostatin within distinct cell types in the early sheep fetal pancreas.