 They hypothesised that the submucosa was not compact as it was previously seen on histological analysis but form a reticular pattern.To confirm their findings, they performed fixed samples of bile duct into a freezing media in order to conserve the shape of the submucosa.They then performed a histological analysis and with several staining technics, they described the submucosa as a network of collagenous bands separating open, formerly fluid-filled spaces.