Ontogeny of the Human Pancreas

Pancreatic disorders are the most common pathologies in humans worldwide. Detailed information on pancreatic cytoarchitecture, vascularisation, innervation, morphogenesis, and cell differentiation is required for the development of new approaches to the treatment of these diseases. Currently, the majority of studies on pancreas development are performed on experimental animals (mainly rodents). Studies on human pancreatic prenatal development are restricted in number by ethical constraints and some technical difficulties. However, interspecies differences in pancreatic structure and development are considerable. Therefore, data obtained in experiments on animals and cell cultures must be supplemented with information obtained directly from human pancreatic autopsies. In this chapter, we summarise our previous results and the literature data on human pancreatic ontogeny. Special attention has been paid to the endocrine pancreas, which undergoes morphogenetic restructuring during human development. Several forms of structural organisation of the endocrine pancreas (single endocrine cells, small clusters of endocrine cells, mantle, bipolar, and mosaic islets) gradually appear during development. It is important that this restructuring is accompanied by changes in the ratio of pancreatic endocrine cells. The mechanisms of these changes are still unclear. The difficulties in identifying progenitor cells and tracking cell differentiation are the main problems associated with this issue