Morphogenesis of the ventral pancreas anlagen is influenced by the SMA branching pattern.

Developmentally, the uncinate process of the pancreas is derived from the ventral pancreatic anlagen, supplied by the superior mesenteric artery (SMA), and contains pancreatic polypeptide (PP)-rich islets of Langerhans. In contrast, the other parts of the pancreas originate from the dorsal anlagen supplied by the celiac system and contain PP-poor islets. This study was performed to investigate whether morphogenesis of the ventral pancreas anlagen is associated with the pattern of SMA branching. SMA branches to the pancreatic body were dissected in 44 cadavers. The cadavers were divided into two groups: the SMA group in which the SMA gave off branches to the pancreatic body and the General group in which it did not. In the SMA group, the ratio of the diameter of the SMA branch supplying the pancreatic body (SMA branch) to that of the SMA itself was calculated. After dissection was completed, tissues were collected from all pancreatic specimens for HE staining and for immunohistochemistry with PP and insulin antibodies. There were 25 cadavers in the General group and 19 in the SMA group. In 10/19 cadavers from the SMA group, PP-rich islets were confirmed in the pancreatic body. The SMA branch diameter ratio was significantly smaller in the SMA group cadavers with PP-poor islets (n = 9) than in cadavers with PP-rich islets (n = 10) (P < 0.001). These findings suggest a relation between the SMA branching pattern and the distribution of PP cells.