THE MECHANISM OF THE GALL BLADDER

Abstract

By a method of filling the gail bladder with iodized oil at laparotomy, and allowing the animals to recover from the operation, experimental subjects in normal condition are obtained. Due to great opacity of the oil to x-ray, slight changes in shape of the viscus can easily be observed, either fluoroscopically or by serial roent-genograms. The contents of the vesicle are expelled during digestion by muscular contraction. Respiratory changes, struggling of the animal and other extrinsic factors produce no expulsion of oil, even after the sphincter of Oddi is cut, the gall bladder remaining inactive and unchanged until the animal is fed. During digestion of protein or fat, if the animal is in good condition, the gall bladder generally elongates, sometimes developing contraction rings, and then expels its contents in varying amounts, at varying intervals, over varying periods, and to varying degrees. It may completely empty and go into spasm. When the stimulus to emptying ceases, the viscus, if not empty, relaxes and reverts to its original shape. Smooth-muscle stimulants induce changes in shape, contraction rings, and the expulsion of iodized oil. The gall bladder empties normally after both vagi and all splanchnics are cut, and even after severing all nerves in the gastro-hepatic and duodeno-hepatic ligaments. The only function of the so-called sphincter of Oddi seems to be to furnish enough back pressure to allow the gall bladder to fill during intervals of digestion, but not to keep it full.