Gallbladder epithelial cells. Coloured scanning electron micrograph (SEM) of epithelial cells forming the internal lining of the gallbladder. The epithelial cells have microvilli on their surfaces. The gallbladder stores bile produced in the liver, and releases it to aid in the digestion of fats. Waste products from the liver are stored and excreted as part of the bile stored in the gallbladder. Magnification: x2000 when printed at 10 centimetres across.