Development, differentiation, and regeneration potential of the Vervet monkey endocrine pancreas

Using immunolabelling techniques, characterization of the Vervet monkey pancreas included a study of both its development and its structure and normal functioning in the adult. We found that PP and somatostatin occurred during development before glucagon. Insulin and all four pancreatic peptides occurred in one of the primordial buds prior to fusion. These finding call into question the suggested contribution of only PP cells by the ventral bud and non-PP cells by the dorsal bud. Co-localization of glucagon and PP was observed extensively with their relative expressions occurring in what appeared to be an organised non-random manner. Cells expressing both glucagon and PP persisted in the adult, together with many other combinations, suggesting an interesting plasticity of endocrine cell differentiation in the adult. Cellophane wrapping of the head of the Vervet monkey pancreas was shown to result in a noticeable increase in duct cell proliferation and endocrine cell volume but no increased replication of endocrine cells. Cells, immunoreactive for pancreatic peptides, were observed to bud from the ducts, suggesting a regeneration of endocrine cell tissue by neogenesis, although it is uncertain whether the duct epithelium contains the only stem cell source of new endocrine tissue. Hopefully, further investigations will elucidate a mechanism by which endocrine cell regenerative capacity can be stimulated in diabetics to overcome their absolute or relative deficiencies of insulin production.