Pancreatic Development and Annular Pancreas

Expansion

• Ventral bud - arises with the hepatic diverticulum; rotates clockwise behind the duodenum to lie posteroinferiorly. Forms the uncinate process and part of the head
• Dorsal bud - forms the rest of the head, plus the neck, body and tail

Two anomalies follow from this:

• Annular pancreas - the ventral bud rotates in both directions, or fails to rotate correctly, so pancreatic tissue encircles the second part of the duodenum. Causes duodenal obstruction, with a double bubble sign on radiography, and is associated with Down syndrome
• Pancreas divisum - the ducts fail to fuse

The islets of Langerhans arise from the same endodermal tissue and scatter through the gland, though they are most concentrated in the tail, which is why distal pancreatic resection has a greater impact on glucose control.