Fig 2.

Stage 5NL IPCCs express several characteristic pancreatic β cell markers. Images in A–J were obtained by confocal microscopy and are representative of at least 12 samples for each immunohistochemical probe. Samples were processed identically and in parallel for each immunohistochemical probe. Immunofluorescent staining of adult pancreatic islets and stage 5NL IPCCs for insulin and C-peptide (A and B), insulin and proinsulin (C and D), Pdx1 (E and F), GLUT2 (G and H), and glucokinase (I and J). (K) RT-PCR analysis of IPCC gene expression during stages 1–4, and in handpicked stage 5NB and stage 5NL IPCCs, and wild-type pancreatic islets. Islet-1 and neurogenin-3 are transcription factors required for islet formation in mice (29, 30) and nestin is an intermediary filament protein (2). In stage 5 IPCCs, we detected carboxypeptidase A but not pancreatic amylase, both products of pancreatic exocrine (acinar) cells. Amylase transcripts are routinely detected by RT-PCR in pancreatic islet preparations because of adherent acinar cells. Other gene products are described in the text. (L) insulin release by IPCCs on exposure to 25 mM glucose. Results show insulin release by 10 IPCCs per time point.