Bile duct. Coloured scanning electron micrograph (SEM) of a fractured bile duct. The bile ducts transport bile, produced by the liver, to the gall bladder and on to the small intestine. The inner lining of the bile duct consists of columnar epithelial cells (yellow). These are surrounded by the lamina propria (brown, bottom), a type of connective tissue that is highly vascular and supplies blood to the ducts. Bile is an alkaline liquid that aids the digestion and absorption of fat and fat-soluble vitamins in the small intestine. Magnification: x 110 when printed 10 centimetres wide.