Pancreatic polypeptide (PP) progenitor cells are immature precursors of the endocrine PP-producing cell type. These progenitor cells are committed to the PP lineage and express early markers, but do not secrete the polypeptide hormone. Although pancreatic polypeptide mRNA is detected from E10.5, presumably expressed by the PP progenitor cells, the hormone-secreting pancreatic polypeptide cells are the latest to mature in the developing pancreas and can only be detected from E16.5.
In the pancreas, endocrine cell differentiation is non-synchronous and lasts from the secondary transition stage (which is the primary period of endocrine cell differentiation) to the postnatal stage.
In the human pancreas, two types of PP-cells are observed: one with small granules and the other with large granules.
EMBRYONIC DEVELOPMENT & STEM CELL COMPENDIUM
