Biliary System Resin Casting: A Technique for Analyzing 3D Architecture of Biliary System in Murine Model Using Radiopaque Resin Injection

The biliary system consists of the liver, gallbladder, and a network of ducts that join to form the common bile duct or C-B-D, which transports bile to the intestine.

For biliary system resin casting, take a mouse that has been perfused to remove blood from the liver and gallbladder.

Place the mouse in the supine position.

Visualize the abdominal cavity under a dissection microscope to locate the visceral surface of the liver to identify the sphincter of Oddi - a muscle layer present at the distal end of the CBD before it enters the intestine.

Make an oblique incision in the CBD next to the sphincter of Oddi.

Insert tubing into the CBD. Connect the other end of the tubing to a syringe containing a colored and radiopaque resin suspension.

Inject the resin suspension into the duct.

Resin moves from the CBD into the network of smaller biliary ducts, eventually spreading inside the liver and gallbladder. The spread can be tracked by visualizing the movement of colored resin through the terminals of small ducts.

Remove the tubing and allow the resin to polymerize.

Obtain the micro-CT images of the ducts. The resin being radiopaque does not allow X-rays to pass through it, providing a contrast to the biliary system and helping in analyzing its 3D architecture.