Bile duct. Coloured scanning electron micrograph (SEM) of cilia (green and yellow) and microvilli (green and pink) on the internal surface of a bile duct. The bile ducts transport bile, produced by the liver, to the gall bladder and on to the small intestine. Cilia are microscopic hair-like projections that beat in wave-like motions to propel the bile along the duct. Microvilli are finger-like projections that increase the surface area of the epithelial cells. This allows them to reabsorb more water and small molecules from the bile. Bile is an alkaline liquid that aids the digestion and absorption of fat and fat-soluble vitamins in the small intestine. Magnification: x3000 when printed 10 centimetres wide.