False-colour scanning electron micrograph (SEM) of the wall of the gall bladder. This lining mucosa, made up of columnar epithelial cells, is thrown up in a series of folds. Beneath the folds lie sheets of smooth muscle. The gall bladder is thus a muscular sac, attached to the liver. It collects and concentrates liver bile. The folded wall increases the absorptive area in contact with bile, allowing the gall bladder to concentrate bile. Bile is then released from the gall bladder down the bile duct and into the duodenum, where it aids in digestion of food by emulsifying fats. Magnification: x160 at 6x7cm size. Magnification: x250 at 4x5 inch size.