An experimental study on the isolated lateral semicircular canal of the bull frog.

The lateral semicircular canals of bull frogs were isolated and the cupula was removed from the crista and the sensory cilia on the crista were depressed toward the utricular side by a glass micropipette. Five points on the crista were selected for stimulation. Decremental time constants of the lateral ampullary nerve action potentials were measured. The longest time constant was obtained from stimulation of the wide portion of the crista. The time constant progressively decreased as the narrow side of the crista was approached. These results indicate that the lateral semicircular canal crista is equivalent to the halved posterior semicircular canal crista in terms of both morphology and physiology.