Zebrafish sox9b is crucial for hepatopancreatic duct development and pancreatic endocrine cell regeneration

► Zebrafish sox9b expression marks all the hepatopancreatic ducts throughout development. ► In the pancreatic ducts, its expression is localised in pancreatic Notch-responsive cells reported to be progenitors. ► Hepatopancreatic duct formation and differentiation are compromised in sox9b null mutants. ► Pancreatic secondary endocrine cell formation and regeneration in zebrafish larvae require sox9b.