ABSTRACT
Just over 20 years later, following the discovery of x-rays by Wilhelm Rontgen, radiologists and gastroenterologists were able to directly study the passage of content through the digestive tract. e ability to follow the dynamics of the movement of content through the gut quickly followed with the advent of long-duration x-ray cinematography. ese studies were performed before the dangers of exposure to x-rays were known and their prolonged nature allowed for detailed descriptions of transit through the esophagus, stomach, small intestine, and colon. While this type of investigation is no longer permissible due to the appropriate application of ethical constraints on excessive x-ray exposure, many lessons can be learned from these early data. Close study of this material shows that the gut undergoes many types of contraction along its length, some of which are purely propulsive, as seen in the esophagus, and other forms of which provide mixing and arresting functions that are assumed to ensure that, in health, the imbibed material traverses the gut at the correct speed and that the correct amount of nutrition is extracted from it at each location.
