Phrygian Cap Appearance of a Mouse Gallbladder on Magnetic Resonance Imaging

We used live-animal magnetic resonance imaging (MRI) to examine the gallbladders of male mice. These healthy mice were fasted overnight before the study and anesthetized in an animal chamber, with a gas mixture of oxygen and isoflurane for small animal MRI. In the course of these live-animal MRI studies, we observed a Phrygian cap appearance to the gallbladder of one healthy-appearing 6-week-old male mouse, similar to that of the human gallbladder described in many reports. After euthanasia for measurement of bile content, this mouse's gallbladder appeared anatomically normal. To our knowledge, this is the first report of a Phrygian cap appearance of the murine gallbladder.